Sister's respect of boundaries

I really don't know if I should post or not but the following affects me quite bad - hoping to solve the situation since nothing I tried did. I

So I M (23) still live together with my mother (48) and sister (17).

[Where I live rent is very high and I'm still at university so my only option If I want to get a good job later on is to stay living there until I get my degree]

My sister has a boyfriend (19) and that makes me very happy for her.

I don't really like him but that's not the problem here - I haven't told her that and also won't in the future, like I said I am genuinly happy for her even tho I don't like him.

Our rooms are wall to wall. So when they started making out (the whole birds and bees stuff not just cuddling) i felt really embarassed. But at that point didn't talk to her bc I thought she doesn't know that I am able to hear that and didn't want to confront her about such personal things. Well - after the third time i heard them I did confront her. I told her that when her boyfriend is over they aren't very silent and that I am so sorry for talking to her about this but at the same time wanted her to know that others can hear her. What she then said to me baffled me: "I know that the walls are quite thin and you can hear me and It could be an bit unconfortable for you. Why do our rooms have to be next to each other on the first hand? Where else should I do that?" I then replied: "I am not mad at you or anything but I as your older brother feel very unconfortable hearing you. Please just don't do it when I am in the room next to you. Next week for example I am longer at uni." She then said: "I don't want wait for you to be away that feels so strict". Then she left.

I started hearing it again just a few days later as if our convo did not mean anything to her. After an couple more days I talked alone to my mother who said: "I will talk to her but won't be able to prohibite it, she has the right to do in her room what she wants. But I can also understand you" (Which of I agreed.) I hoped it would get better after that but nope. I started to not talk to my sister when we saw each other bc I felt just very uncomfartable hearing my sister moaning so often. Every second day he is here and every weekend he sleeps at least one night here. During daytime even tho I want to stay in my room I just go to the kitchen and stay there until he lefts since they always make out when he is here. But when he sleeps here, that is the most difficult part. They do it the entire night. I tried making loud noises like dropping things as hints - they ignore it. Then I had a talk with my mom and sister together - again to no prevail. My sister showed no understandment why I had an problem with the situation. I had an day where I just laid in bed from morning till late afternoon, unable to eat anything and just wanting to sleep. My mother got very worried and picked up that it was stress from the situation, but nothing changed. An couple days later when I was in the kitchen and he left my mother said "he left, you can go into your room now" - which also didn't feel good. I am writing this entire rant at night while they make out.

My sister told on my mom that I never talk to her and she misses talking to me. Its not that shes talking and I am blatantly ignoring her she herself doesnt try to strike a convo. But like I said I feel unconfortable around her which I actually don't want to and it all makes me sad. She is very mad at me (visibly and verbally whenever I try to explain to her that I already explained the problem I have with hearing it.) and then tries to brush it off as an problem I have with her.

What should I do? Did I do anything wrong? Is she right for that I am being an a hole for not talking to her as freely? Is that actually all normal and I do indeed am the one with the problem?

Some additional Infos: I myself don't have a gf but if I did I would want to be alone with her and feel icky with my mother and sister in the house when doing it. If it would come to the scenario where she would be the one to confront me I would apoligize for her hearing that and that we would stop doing that when shes there (But it wouldnt come to my mind in the first place, making out with my gf while my sister is in the room next to me - that just feels wierd and wrong to m**e). She never is at his place - he has a car my sister doesn't but with the train it would be like 1-1/2 hours the same time he needs with his car when driving to us.

My mother also doesnt want to switch rooms with me which I asked her before as an possible solution. My sister also doesn't want to switch rooms with my mother bc she enjoys the view from her window too much.