TBH, if she isn't pregnant now, she has been in the past, which means she probably will be again soon, within a month or so. If you've ever seen a 'virgin' female platy, their tummies are fairly flat, similar to a male, but I've found once they've been pregnant once - they tend to look all round pretty much all the time - and when they're about to drop fry, they look fit to burst. Your's is definitely somewhat rounded.
I don't know what you lot are going on about with defined gravid spots - I've found my female platies to never really have a gravid spot (not likeyou would see on a guppy anyway - very dark and defined) but rather, I can see lots of tiny little dark dots inside her - these are the eyeballs of all the fry. Yes, you can actually see the eyeballs - the lighter coloured your platy is the better you can see them. Also if there's a bright light behind them.
I disagree with those who say fry will survive in a community tank - unless I put the expectant mother in a trap (if you do this, learn to time it well - being in the trap for a long time if its not ready will stress her - you will learn to see the signs she is ready) then I never have ANY fry survive in my (planted) tank. They are gone within a day - less even - one night the mum is full of eyeballs, the next she's not, and not a fry to be seen! But happy looking gouramis, platies, and tetras (pretty sure my cories aren't responsible!). So, IMO, if you want guaranteed survivors, they need rescuing. Depends on your inhabitants of course.
Good luck, I'm sure you'll eventually have fry in no time.