S.S.
I, too, recommend flylady.net. I've been getting the emails for a few years and it's really helped me. I've read lots of testimonials from people with situations like yours and how much her system has helped them. I have three kids myself and health issues that affect my energy levels. I could not do it without flylady. The emails can be a lot, but they help keep me on track and if they're too much, that's why you have a delete key. :) There's also a link to what sounds like a really fun way to teach kids how to clean: www.housefairy.org. I haven't tried it, but the testimonials about it sound very promising.
If you can, I also recommend finding a housekeeper, at least while your kids are so little, to take some pressure off yourself. Having small kids and health issues can be very overwhelming, so it might be worth the investment. I found a housekeeper who is willing to put things away and change linens, as well as general cleaning. Unfortunately, her schedule is full, or I'd give you her name! But try looking on Craigslist or on the Mamasource site, or even call churches to find someone you can trust.
Good luck! I hope you find something that works for you!