I [M/23] feel like my gf [F/20] is getting more distant.

We've been together for a year and it's been pretty serious. However, it just feels like she's been more distant over the past month or so. She works part time and goes to class, so I'm trying to understand that she is busy and I really don't want to be needy. However, we used to hang out a lot and just have fun. Our sex life has reduced drastically, maybe once or twice a month we do it. It also feels like she's hanging out with her new roommate [F/23] a lot more which I've actually been encouraging since she had such bad roommates before (and I mean BAD). However, she'll go to these events with said roommate and not even bother to mention it to me. I trust her and her roommate (roommate is crazy religious so it's not like they're going out hardcore partying). More often than not in the past month or two if I don't text first I don't hear from her at all.

I've asked her to make plans since it feels one sided, and she agreed that it has been one sided and that she will do better. I'm not seeing much improvement with that, but she is a very shy person so again I am trying to understand.

On too of the distance she also talked about meeting her parents (she's already met mine) over winter break, but she cancelled that idea. We also never met once over finals week even to say goodbye before she left for winter break. She left today to go back home and didn't even tell me. I found out because she got tagged in a pic from her dad that said they were going back home. Her family knows about me, so Idk why I couldn't meet them while they were visiting. I brought up the idea, but she was kind of wishy washy with it.

This is my first relationship and I don't want to be needy, but I'm just not feeling needed or wanted. Am I being irrational?

Tl;dr I don't feel like a priority, and while I want my gf to succeed and make good friends, I don't want to be put on the backburner or always be an after thought.