They get VERY large in the belly area, she also will probibly start to hide from the other fish, and depending on the coloration of the fish you may see the Gravid Spot...
Yeah.. the only way to tell is that they become HUMONGOUS.
But sometimes they dont. My balloon molly had babies the other day and I didn't even know she was pregnant. But she only had like 8. So. Ya never really know for sure.
Reddish? Is she, by any chance, a light color? Because then it would be the gravid spot. If she's not light...that's not really normal. The fry could have turned around, or she could have some internal bleeding...but it should usually be brown or black.
Probably more will come. Unless they haven't already come and been eaten.
Usually the fry birthing is spread out a little. Some will have all their fry in a few hours, some take a few days. Just keep the enviroment as stress-free as possible, and you should have more fry.