Should I stand up to my girlfriend or am I being sensitive?

I've been with my girlfriend for over a year now and we recently started having some issues. She has been feeling depressed because she feels I can be to clingy and that I have jealous and temper issues. I've realized these issues well before we dated because I've had other long relationships and they ended badly because of me. I'm trying very hard to work on my issues and so far she has been very understanding of them. However, lately she told me she has been feeling depressed because she feels that she can't act as herself because she thinks I get upset and roll my eyes. I agree sometimes she can make jokes and act crazy and I get a little irritated but now she is just being overly obnotious about it and i wonder if it's because she is trying to test me or maybe I'm just being sensitive about it? For example she called me the other night talking to me on the phone and she was walking with a friend. She asked if I wanted to get food but I wasn't around to (we go to same college, live in dorms) so in front of her friend she was just like oh you whore and giggled. I shrugged it off and was like ok, if I want to keep her I just gotta let her joke how she wants and forget about it. Then today I met her at her class to surprise her because I was wearing a shirt she got me and shaved a goatee the way she has been telling me to cuz she thinks I would look good. Anyways we were walking and she had another friend with her and my girlfriend ended up dropping her coat and i ended up picking it up for her and she just looked at me and responded with "thanks slave." Now I know she's a jokester and all but should I be taking these things to heart or am I just being sensitive? Lately we just feel like we're on a downfall. Also another instance is she has been stressing over a 20 page paper thats due soon for finals and i've been trying to help her with it and getting her to work on it. I suggested we get as much done so we can go on a date night together because we could use one. She was like ok i'll try and get some stuff done. Well anyways she told me her friend invited her to a party and my girlfriend was told me and was like I need to get this paper done so I can go to the party. I just don't get it, she procrastinates when I ask her out on a date and she doesn't get in a rush to finish the paper, but when someone invites her to a party she wants to rush to get it done. I'm just at a loss right now. Is she just trying to be free and start to let go of me or am I just over thinking everything? Sorry for the length. HELP!