It sounds like the only real reason you are working right now is to keep your foot in the door. Working isn't helping you financially, and it is just adding to your stress level, especially since you aren't happy with the childcare arrangement you have.
I understand that you want to use your degree and have some adult interaction, but you could always just make yourself available to pick up occasionally. You can find more fun ways to find adult interaction, too. Or, you could try to keep in touch with your current co-workers. That would keep you in the loop, help you keep up with changes in your company, keep you in their minds, and also give you adult conversation.
Your kids will only be little for a short time, and when they are in school you can go back full time if you want to. Is there anything you can do to make money that allows you to stay home, or only work when your husband or a friend watches your kids? Sell things on Ebay, sell Mary Kay or Pampered Chef or something like that? Or work as a consultant? Or take care of a kid or two in your home?
The only other thing I can think of if you really do want to work, is to change preschools to one you think you will be happier with and is cheaper or switch to a good babysitter (I know, tall order).
Personally, I think that work will always be there, but your kids are precious and grow up way too fast. You can't ever go back and do that over. Nobody ever gets to the end of their life and says "I wish I would have worked more"!
Good luck.