Relationship issue that I really need help with!?

Okay so my girlfriend is having a bit of an issue...with me. But they're issues that don't really exist as she says. She gets annoyed with me over really small things that don't actually matter. She says that they're things that shouldn't annoy her and in most cases she's right. She gets annoyed over things like me having my feet pointed inward or me saying I don't know too much (the I don't know thing to me is a good reason) but the thing is she's done this before and I fixed the problems, most of those were reasonable. But now she found a few more things. Now years ago before I knew her she dated and got engaged to a guy that was in the army and came back and broke her heart. Now she has a fear of being with the wrong guy and getting divorced. She has dated one other horrible uncaring sbag since then. Now my theory is that since she is afraid to marry the wrong guy get divorced and have a broken family like her parents she may feel I'm the right guy and is sub consciously protecting herself from getting hurt by making me seem like the wrong guy to give her a reason to leave. We both love each other VERY much and have since we've been together (8 months) I really love her and couldn't live without her so we need help with this. Tell me what you think it could be or how to fix it please...I don't want to lose her I really feel her and I are made for each other!