Sexing Mollies/ Molly Pregnant

Hey all,

I got my first Molly a few weeks ago (number 1) and two more last week (2&3). I had believed that 1 was a male while 2 & 3 were female. To determine this I just looked online at photos as well as Molly 1 has been chasing the other two.

But over the past few days Molly 1 has been looking larger and larger as if he/she is pregnant. Do you think I should be preparing for spawn??

Edit: link to photos because they didn’t seem to load - https://imgur.com/gallery/Ab2Gv0p

PS. They do have names - Shelby, Mia, and Wiz!