Your biggest problem right this moment is that your tank was JUST set up. You need to be sure not to get ANY more fish for awhile, no matter what your real setup will be like. You need to read the stickies at the top of the beginner forum about cycling your tank and setting up your first tank...because your tank is 'cycling' right now. The more fish you add the higher the ammonia and nitrites will get even faster.
Since you dont have test kits right now you should do a 50% change asap and then get the tests. Chances are good that you'll need to do a lot of water changes to keep the ammonia and nitrites at a liveable level for your fish for a few months...and then one day they'll both drop to 0 and your tank will be safe for fish.
As for an eventual stocking plan you want to stay away from having male and female platies in the same 10g because they tend to overpopulate the tank. Try getting only male or only female platies. If you really like the smaller fish, they really are better for a small tank...you can get more and usually they're less messy. If it were my tank I'd look at all of the small fish, pygmy cories, otocinclus, harlequin rasboras, cardinal and neon tetras, ember tetras etc...and then 10g tanks are also good for critters like apple snails and shrimp instead of plecos. Why dont you take a look at our profile section while trying to decide what fish you really want?
http://www.myfishtank.net/reviews/index.php
oh...and you may want to talk to your mom and let her know that getting you more fish is a sweet gesture, but right now they'll probably just die so ask her to hold off a couple of months and then you can tell her when the tank is safe and which fish you really want. Or better yet tell her to save her money and get you a bigger tank