I think my girlfriend is ashamed of me

A couple weeks ago me and my girlfriend were sitting at a bus stop and a lady came up to us. she began talking and having a conversation and then she asked if we were sisters. my girlfriend said "no no we're friends" later when we went on the bus I asked her why she told the lady we were friends and she was really confused, she asked me "what else was I supposed to tell her" and when I said that maybe she should have told her that we are a couple she said "I'm too scared to say that older person" again this was a really nice older lady and what's the worst thing that could happen anyway. A couple months back I was at our friend's house, a couple people were hanging out, and she joined a bit later. I tried to kiss her hello and she turned her head sideways. mind you our friends knew we were together at the time. I was really hurt by that, I didn't say anything though. that was a couple months ago and I was just scared to talk about anything with her. A couple days ago she passed her driver's license exam and I tried to congratulate her and kiss her and she also turned her head sideways and we were with our friends but we kissed in front of them earlier so it wasn't them. I waited for the others congratulate her and I just sat down and later when we were walking she tried kissing me multiple times and I didn't let her, which I feel really shitty about, but u felt sad and rejected and maybe even angry, she said and I quote "I'm so sorry but my instructor was there and I might see him again" and is that a problem that someone you know will see me kiss you or see me with you? but we haven't kissed since and she didn't really talk about it after that, she only asked me once if she could kiss me, so she obviously realized i stopped kissing her, and I told her no, im a fucking idiot. and I'm not really ready to talk about it, i just told her so many things that really bother me in our relationship and i encouraged her to tell me what bothers her or what i should improve. she said im doing nothing wrong and the general conclusion pf the things i asked of her was "I'll try but i don't think i can" Which i dont think i asked putlandish things but thats a different post. Either way we're kind of on thin ice and we've been togethwr for almost 2 years (f16 and f17) so im scared to start something again