How do you not worry about your girlfriend?

not if you trust her :)

If she takes a pregnancy test and returns positive, you should start worrying then (if you weren't worrying already).

It means he cares about you and he more than likely wants to be with you but he wont admit it because he is a guy in the future i will guarantee that he will ask you out

You don't need to worry about anything whoever you are and where ever you are cause it will be sorted out one day

if your girlfriend has a girlfriend, then she might not fully understand the concept of a faithful relationship, and is clearly Bi-Sexual. just let her know easily how you feel about that, and ask...