I have read about the inch per gallon rule however i have read that its different with smaller fish such as tetras and otos. So heres my stock so far.
10 neon tetras
4 mickey mouse platys(daughters pick lol)
Too many ramshorn snails
5 or 6 ghost shrimp
My filter is an eheim 2215 can i add like 5 more neons and a couple more platys?
Your platys may soon start producing their own live food - I once watched a female giving birth whilst the dad hung around behind her eating whatever came out. Pretty savage..I'd say you have room for more tetras but I'm a sucker for big groups of one species - maybe get some glowlights or black neons are pretty fish - they will school together but in their own groups at the same time if that makes sense. Just increase your water change routine to more frequent smaller changes rather than say one weekly large change to help keep conditions stable.