Trust is important in a relationship and mutual.
However, i am going to say that, some people just abuse with this
trust. If you give them too much of it, that they took for granted
and began to play with your feelings.
so... i'd say, if you think you're over sensitive, then you should
start talking to your gf about it. Talk it carefully, slowly and
most of all, you must say the truth and respect whatever decision
she comes up with.
Work something out. It's no use thinking now later, or
forever.
No use if you don't think either.
Let actions do the talking.
Tell her sincerely how you feel about this situation..