First off if you keep calling them chick they will stop telling you to come over.
Anyway, you don't show then to your friends because you are insecure in some way. Has this happen before when you showed a girlfriend to a friend she went off with him? A real friend shouldn;t steal your girfriends so you have nothing to worry.
As for having a low sex drive I am going to say that its normal and you only being 16 doesn't need to have a goal to be with every girl in the school.