Why Am I So Mean To The Nice Girl In My Dorm?

So here's the thing. I'm Alice, and this is my first year at college. I moved out of the dorms last week after a few days and found an apartment closer to campus since I didn't like being with strangers. But then, this nice girl named Lisa moved into my old room in my building. She's really friendly and always smiling, which honestly makes me feel uneasy. It sounds so petty when I say it out loud, but she's just... too nice for some reason. I keep finding myself snapping at her over small things. Like the other day, she left a note on our common fridge inviting us to grab coffee together in the morning and I ripped it off without even thinking. It felt like a reflex, an automatic response to something that should be harmless but somehow isn't for me. Yesterday, Lisa was talking about how much she misses her family back home and said she loved cooking for them. And right after she mentioned her favorite dish, my stomach growled super loud (like, embarrassingly loud). It's like I can feel this tension building up between us and every little thing sets it off. I've never been someone who struggles with being nice to others or feeling uncomfortable around a friendly person before. But lately, Lisa seems to just bring out the worst in me. Every time we're near each other, my guard goes up and I feel like I'm waiting for her to do something that sets me off completely. I wish there was some way to make things better between us but honestly I don't even know where to start. Maybe if she didn't care so much about being friendly all the time? But who am I kidding, it's not her problem that I feel this weird anxiety around her. So now I'm just stuck feeling guilty and scared every time we cross paths. I guess what bothers me most is that Lisa has been nothing but kind to everyone here, including me, yet somehow she rubs the wrong way so much. Am I really being an asshole for no reason? What's going on with me?