My roommate doesn't respect my boundaries. (both f18)

As the title says, I dorm with my roommate. Initially, everything was fine because we were figuring out college life and getting used to living in a small space together. Around late September, she started bringing a mutual friend to the dorm, and she would stay until 9 PM. I was fine with it at first because I am socially awkward, and it was nice having some company. But in early October (before our fall break), I had enough. They were loud and she would stay until very late, one instance I was Facetimeing my mom, and couldn't hear my phone. After that, I spoke to her and told her my grievances, which she worked on. Then weeks after break, it resumes. I sent a message to her after that, basically reiterating what was already said to her face-to-face. I went to the RA, and my roommate didn't like that and told me if it was super important we could have a meeting with the RA. I told her straight up that it felt like I was being kicked out of my dorm and that I wasn't welcome. We ended up making a schedule and it was working. (I have a lot of meetings during the week, making it frustrating when I want to relax and see a guest in the room, with no warning). I wouldn't be making this post if it was still working great. So this week, she came back from home and started up with having the friend in the room all day, every day. I told my mom about it (I usually run to her for help), but IMO she wasn't helping much. I'm tired of having to say the same things over and over, but I feel like I am out of options. I bend backward for her, but I can't get the same respect. My boyfriend and family think I should confront both of them at the same time, but I feel like it is unfair to the friend (who I think is innocent in this). I am at my wit's end, if there is anything you could say that would be very appreciated. I am aware I will have to speak to her about it again, I am just emotionally tired from all this.