Well, it had ME fooled...you could add a big wad of Java moss for cover and a bunch or two of cabomba or hornwort. My platy mommas are really unhappy in a breeder net (they go spastic!). You were going to need another small tank for the fry anyway, right? ...why not heavily plant that and put momma in there before she drops; then remove her after they show up. Once the next lot comes around, the fry will be likely too big for her to eat even if she wanted too....and they usually don't bother.
Is is me, or does the pic look like 2 "variatus" platys...and one "maculatus"??? That might explain why she looks fatter. Look at her head on or from behind...they look ready to explode before they drop.
BE PATIENT...Took a couple of months for my first fry...and I got ONE.