It would appear that I still have fish!
I finally cleaned the tank for the first time in far too long and it appears that I still have most of my fish. There's only one Otocinclus left, but I hadn't seen any for weeks. And I think one of the baby Macropodus didn't make it.
Cleaning and a water change (and more importantly, addition of new water) has brought the tank to life. The platies are going crazy. Amazingly, in a tank full of semi-aggressive fish (seven Macropodus in there right now) it's the platies that are doing the most fighting. One of the "younger" males seems to be challenging the largest of the "older" males for dominance. Fresh water always brings platies to life - not that the males don't harass the females all the time anyway.
I'm really not sure what the deal is with the female platies. I have yet to see any more babies, but in the current set-up, I doubt they would survive (the Macropodus and the angels are good hunters, and there are just too many of them). While I was convinced that I had never seen any of the females get any slimmer, I am no longer able to say that definitively. I just didn't pay enough attention to them for a length of time - and some of them don't seem as fat as they used to be. One of them has gotten huge.