Quite possibly, but with the colour and shape right now, can't tell if she's gravid or bloated. If there's a male in the tank or she's ever been near a male, then she will be sooner or later!
There’s no males in the tank but our other molly has had fry’s twice now so guessing it happened at the pet shop! No other concerns at all! Thanks for the reply!
White stringy poop is likely mean worms. Which I think are common enough with livebearers. I had to do worming treatment recently on a livebearer tank. @AdoraBelle Dearheart did too.