It's silly but please hear me out I'm scared

So, I met my boyfriend through Hinge. We started dating around 5 April. He was perfect, and honestly, he still is. But I'm really insecure, mostly because I've never had a genuinely healthy romantic relationship before. The last relationship I had was when I was 14. It lasted for about a year and ended pretty badly. I'm 20 now, and he's 20 too.

He's my first kiss and everything. He's the first person I've even given a cheek peck to, so you can probably tell how inexperienced I am. Meanwhile, he had a 4-year relationship before me. He told me she cheated on him, but still, it makes me insecure.

My first insecurity is that I don't think someone can ever truly move on from their first love, especially when they've been together for 4 years. He told me she was the prettiest girl in his school. And after they broke up, he went through a sleeping-around phase. I don't know the exact number, but it was roughly 20–30 girls.

My second insecurity is that he's way more experienced than me. Most of the time, I genuinely don't know what I'm supposed to do, and I keep thinking he must have been annoyed by how inexperienced I am.

I'm also fat, around 70–72 kg. He's a fitness freak, has a really good body, and he's genuinely handsome. Like, handsome handsome. I don't consider myself pretty.

He works and earns money, while I'm still in college and don't even have a definite future figured out yet.

And I'm attached to him beyond repair. I've noticed that his tone has changed a little. He doesn't really make any moves anymore. He has his own life and his own problems, and I completely understand that, but I can't even mentally prepare myself for the possibility of a breakup.

I'm constantly bracing myself for the day he messages me and says he's done with me because I have nothing worth keeping. I genuinely feel like I'm nothing sometimes. And, as a bonus, I honestly have no friends except him. I don't really have anyone at this point in my life.

Sometimes he says things that hurt me, but I don't complain because I'm scared he'll eventually think, "She's too much. I can't do this anymore."

Sorry for writing such a long message, but I'm genuinely so scared and I don't know what to do. I can't even imagine what a breakup would feel like. What am I supposed to do?