Definitely looks that way to me! And I may be wrong, but she looks close to giving birth. You way want to read some articles on steps to take to prepare. Hopefully someone more knowledgeable can give you some advice. Good luck!
This is my first potbelly molly and I think she e is pregnant but not sure. Anyone?
I think she looks pregnant. Does she hover around the heater? That's a sign of pending birth. My 2 females are very plump and seem to give birth every two weeks. They usually stay around the heater or on the bottom corner of the tank.