Hi, SquirtSquirt! I'm so sorry that life has been hard for you- hopefully it will get better.
Everyone here has offered great advice, and my favorite is listing a big picture of what you have. Those pictures are always fun to look at, and you'll get all sorts of offers and PC's on what is there.
The only thing I can add is that the ponies will wait- they will wait patiently while you do what needs to be done, and the ones that are hiding right now will show up sooner or later. Who knows- they might be hiding until their value goes up again! Sneaky ponies. The ones that you've put aside for your little one (who isn't so little now, I'm guessing!)--- did she just never get into them, or did she play with them a lot and then lose interest? If you really need to get rid of them, I understand, but you might want to stow a few away just in case. Granted, if she starts to care later on, she can buy back her own ponies just like most of us had to! It's part of the fun?
Big hugs for you, and good luck! I'll be looking for a post of pictures, just cuz they're fun!