Question about planted aquarium and fishless cycling

I turned the temp up to 78 after my last post when I realized you had suggested warmer. Got the fish from Pets Way, I believe it's a chain store.
The fish doing the chasing is bigger than the male and other female, has a triangular anal fin, is gray with faint tail fin colors, has a very rounded belly with a gravid spot. The other female is actually bright hello with yello and read tail fin (unusual colors for a female I thought), has a triangular anal fin, and a gravid spot. The male has a very bright multi color tail and a long thin anal fin.
My water since the last exchange has been ammonia 0, nitrites 0, & nitrates 20. I removed a plant at the last water exchange that I don't believe was getting enough light. It's leaves were falling off when it was touched.
I will probably wait until the fry are a little bigger before adding more fish. I have only seen 4 at a time but I want to make sure before adding more fish. I know I could add fish that will help keep the population down but I would like one or two of these little cuties to live for my kids.