At the pet store you bought a fat male hamster you have had him a bit less than 2 weeks by reading what people have put about pregnant hamsters he does do these things could it be possible he a her?

Yes it is possible. Often when hamsters are very young it is difficult to tell what sex they are. you can take him/her to the vets to find out, or you can look at some diagrams to demonstrate what a male hamster and a female should look like so that you can sex them yourself.