I have a few suggestions.
1. Find a new circle of friends. If you're nursing, then maybe LLL, or really any mom's group. They're out there. But it's easy to get isolated when you're a SAHM, and that can lead to depression.
2. Find a system for housework. It's really easy to let it go, but I find if I do certain things every single day (pick up, clean bathrooms, keep kitchen clean as I go) it takes SO MUCH less time to keep up on stuff than it does if the places becomes a pigsty adn I have to work for hours to get it back looking decent. Also, if it looks reasonable you well feel comfortable having SAHM friends come over, which can help with #1.
3. I agree about the schedule thing. Find something to do each day, like a destination. Library, museum (if it's free), park, playdate, walk through the woods, whatever. It helps keep the kids from wondering what they're going to do that day. They have something to anticipate. And, again, it can help with #1 as you'll meet other SAHMs.