Looks to be, but not close to giving birth.
Do you have a breeding net? Or place for your fry?
She looks pregnant. My Dalmatian Molly gave birth last week. She will get really square looking towards the end of her pregnancy. Don't expect many fry to survive if you leave them in the tank with adult fish. I only have two mollies and they had eaten all but two fry by the time I noticed them. They hunted them down like lions after prey. I set up a make shift breeding net out of a plastic food container and have it floating in my tank. The adults are still trying to get to the fry.
It most likely the stress of moving into a new tank She should be fine
If you want to know, be very quick with this , take the fish you think is pregnant out and shine a torch through it, look on the other side and you will see fry shapes if she is hope this helps
If you want to know, be very quick with this , take the fish you think is pregnant out and shine a torch through it, look on the other side and you will see fry shapes if she is hope this helps