Until mature platys can be a little tricky sorting out. If yours was a crowded community tank, congratulations in rescuing 8 fry!

A friend and I, visiting a club in Indiana, picked up some very young red swordtails. He offered to give me half of them and because we both have gotten more males than females, I'm glad he did that. We have swapped individual fish in order to keep the strain going at both places. If we swapped individuals every couple of generations, that might also help a tiny bit with a little genetic variance. (I hesitate to call that line-breeding.)

If we are more militant in doing partial water changes, maybe the gender balance will be better. (Knock on wood. "Ow! My head!")

As for Ms. Tangerine being pregnant. She is an adult female livebearer isn't she? She was with male platys? Then she is 99+ % likely to be pregnant. ;)

You sound like a lot of parents. "They grow up so quickly!" <snif>  :)