Prozac, libido, and pregnancy?

i have lost all want to have sex since i started but lately i have been way in the mood (sorry, TMI! lol) it is more of an internal than external feeling though and comes and goes quit frequently during the day. Could this be a sign of pregnancy? it also is enhanced when i have to go to the bathroom, and makes me feel like i have to go take a dump but nothing comes out for at least an hour. any help would be nice!