Really unhappy but can't let myself leave

I'm not happy in my current relationship, when we first begun dating it was a bit rocky but she was affectionate and I was happy.

But i haven't been happy in months, she isn't affectionate in public except for kisses goodbye and the occasional hug or so, I barely see her outside of college and lately barely in college, she told me she wants to be with me but isn't in love with me just loves me and that I can't be a priority to her, I'm off to university soon, she won't do anything sexual with me because she emotionally cannot do it, she isn't open about her feelings but somehow despite being constantly unhappy I can't leave.

She's my first relationship, I'm 18, and she's probably the first girl to show interest in me for a long time but I'm really unattractive physically: I'm really short, a bit flabby, ugly, bad teeth, messy hair and i don't see how anyone else could like me at all

Just i don't want to stay in a relationship feeling like this but I don't want to leave either. Help?

Going to uni will change your life. Don't worry. You're probably not as unattractive as you describe yourself to be.