I had to change my character's original backstory because my DM said "it doesn't make sense"

Hi guys, This is my first time writing on reddit so sorry for any mistakes. Also this is gonna be a long talk (also sorry for that xP)

I recently made a character for a campaign and after 6 sessions I discovered that my DM didn't actually fully understand my backstory (even tho I sent him the backstory before we start the campaign) and went with his own narration and plans for my character. At first I didn't notice, but after few sessions I did, I sat with him after the last session to communicate about my character backstory and how both of us understand it. After the discussion he told me that he didn't know that this is what I meant in the original backstory and then he repeated that it doesn't make sense, I got confused because I saw (and still see) that it makes absolute sense in an emotional and logical way (at least in my mind), then I told him it might be just a matter of taste here but he still disagreed, at the end I accepted his narration for the sake of the campaign BUT... what made mad is this one sentence he said at the end after I got disappointed and told him I swear I saw the same concept somewhere in a movie or something but I don't remember, he then told me "some movies can have a bad plot" This one literally hit me hard cuz I put emotions into this character and so far it's my favorite character that I made in DND (I started DND January 2024 so I'm not an expert but I made a lot of characters before) So for that being said, I wanted to show you guys my original backstory and my DM's edits and share with me ur thoughts and if it actually doesn't make sense like he said or not (I'll try to tell u the backstory briefly)

The backstory: "Finn Vadalise: a druid kalashtar"

In the city of Sharn (a flying island over the content of Avalon) there are several houses that control the city. In one of the houses, there's one house called "House of Vadalise". Born as the sons of the leader of this house, we see 2 twin brothers the first one called " Finn Vadalise " (my character's name) and the other called " Sinnin Vadalise ", both was raised in the household of the father who was a firm and tough individual who's full of discipline and strength, on the other hand the mother was just a beacon of warmth and kindness, her gentle manner and kindness was one of the main reasons of the development of Finn's personality, as he was a gentle, caring and peaceful soul who always seeked peace, and also because of him being one of the kalashtar, he had with him company all the time, this quori monkey spirit who shared with Finn this vessel of a body, the monkey had the name of Po, he was joyful and chaotic and he was always with Finn at his best and worst. On the other hand, we see Sinnin who had a different personality from Finn as he was charismatic and magnetic but he was also loud and sometimes a bit rude to other people, but to Finn, they were best friends (the DM decided that Sinnin didn't want to tell us about his quori spirit for some reason), when Finn seeked peace, Sinnin seeked purpose. The father always saw Finn's pacifism and avoidance of conflict as weakness, he always complained that he has more to him and he's wasting potential but Finn seeked peace always. The years passed till tragedy hit the household of the leader of house Vadalise when the mother died. Every one took the news with grief specially Finn, as Finn got quitter while trying to keep his kind manner, Sinnin also became more quite than before, but the father got more tough and harsh and couldn't take Finn's pacifism anymore, and so he decided. He sent both Finn and Sinnin to an underground fighting tournament so they learn to survive in a harsh environment, Finn tried to resist but his father will was stronger this time. They both went to the tournament as Finn showed skill and adapted to his opponents not to win but to survive, as he disarmed and controlled the battle with the least harm possible to his opponents and showed mercy whenever he could trying to not kill anyone but just to make them go unconscious, which made him likeable for the audience , he did that for every battle as Sinnin was watching him. Sinnin always had this small jealousy of Finn when their mother was alive as he was more likeable because of his kindness, and when their mother died, the jealousy grew even more as Finn got stronger and was better than Sinnin in abilities and combat (mechanically at the time Finn was 5th level druid while Sinnin was 3rd level rogue). And then it happened, the final battle of the tournament, Finn vs Sinnin. Seconds when the battle began, Finn didn't wanna fight and told Sinnin "we don't have to do this" , but Sinnin didn't listen as he started to strike once, twice, Finn dodged and didn't raise even a fist against Sinnin but Sinnin was striking not to win, but to matter, to prove himself once and for all, until he knocked Finn to the ground. And here Sinnin had his chance to win the battle, but Finn looked at his twin brother not with anger but with disappointment, not in his brother... But for him. Sinnin then woke up from this wave of jealousy and anger against Finn, his twin on the ground vulnerabley looking at him with this look, guilt and shame took over him, he had hurt the only one who believed in him, he hurt his best friend, and for what? And so he ran, ran from the tournament, ran from Sharn, ran alone into the land of Avalon. Finn after few days of the incident blamed his father for what happened and so he decided he'll go find his brother to bring him back and show him that he's still loved by his family.

That's pretty much the original backstory of my character. Now I'll show you the edits that my DM had me change in the backstory:

• he said that Sinnin running didn't make sense at all, as he told me that Sinnin not killing Finn is an act of kindness and mercy so why would he run? I told him it's because he felt guilt and shame but he responded with the same answer "it doesn't make sense", I told him emotions doesn't always make sense but still the same answer.

• he told me he'll change it to be that Finn fought Sinnin trying not to hurt him, and when he hurt him accidentally, Finn will heal him until he defeat Sinnin but wouldn't kill him, then Sinnin refuses "Finn's pity" and couldn't take the "humiliation" so he ran away. I told him "okay your narration is good but I still don't understand why should I change my backstory? And tbh I see it as a matter of taste", but guess his answer? xP, he said again that it doesn't make sense

• also at the beginning I told him that Sinnin is a druid and asked him to tell me what would his quori spirit be, but he changed it that Sinnin became a rogue and refused to tell me about his quori spirit.

• another thing is that he asked me about Finn's purpose, I told him that FOR NOW he's looking for Sinnin, he responded with "yeah that's his goal, what would his character development gonna look like?" I was confused by this question, for me as a player I like to make my character development as natural as possible and I told him that but he wanted a clear character development, and told me that he expects Finn going from a being pacifist to becoming a leader who leads people to peace.

I got a bit annoyed tbh as he wanted to control my character's backstory and also his future development, but at the end for the sake of the campaign, I agreed to his narration.

But till now I'm still mad and also confused and doubting if my backstory actually makes sense so I would really appreciate if you guys share your opinions on this.

Sorry about the long talk xD