It's not fat. This "fat" you're feeling is probably just tight skin, which stretches in preparation for intercourse or spitting out a human being the size of a watermellon. If you're concerned though, don't be afraid to talk to your doctor about anything that's bothering you.
It isn't- the walls are really stretchy (think, they have to be able to stretch to be able to fit a baby through there!) and so are bound to feel a little 'puffy'. No one would think you are fat if they felt in there.
i think that is the way it is supposed to be. why dont you go to a doctor to see if that is normal.
may I look at it? ;P just kidding