It's not easy to tell, but that molly looks pretty big to me. My platys typically have fry every month or so (anyone want to take fifteen zillion babies off my hands? ). Based on her size and their short gestation period, I'd say if you've had her for a couple weeks it probably won't be more than another two. I wouldn't move her or confine her - I've had much better luck filling the tank with feathery plants and letting livebearers give birth in the tank. Some fry may be eaten, but those that live are healthy and grow fast.
Sell them, or if they're mixed as mine are (in which case it's not a good idea to sell them) some people give them to friends with cichlids, or to the LFS as feeders.