I'm a painter and a writer and I attend Zumba classes regularly and I'm a SAHM mom with no help, three young kids (Not in school yet) with me full time and a husband who travels. I also participate in teaching things with my oldest daughter's kindergarten homeschool network. Here's how I do it:
Skip housework often. Clean up only the mandatory functioning spaces and leave periphery work for times you can schedule it in. Keep the laundry and dishes done so you can function, but "fancy detailed house cleaning"-forget it. Once a month. If your husband is an OCD neat freak who needs a spotless house, tell him he'll have one when you guys can afford a live-in maid.
I can only pursue one creative endeavor at a time, unfortunately, so at any given time I'm either writing something OR painting for a show. My allotted time for that activity is 2 hours in the morning before everyone wakes up (so I have to go to bed really early on nights before those sessions) and sometimes I get another afternoon window on days where classes and errands are done, kids can be thrown in front of TV for an hour or two. That only happens once or twice per week, and the mornings I can usually do three times per week. That adds up to 10 hours in one week if I stay on schedule-which actually enables a lot of progress.
SCHEDULE. Get a big calendar and block out each month in advance, list EVERYTHING you want to accomplish with your writing in that month. Decide how many hours that would be, 80? 60? 40? Divide it into hours per week, and per day. Schedule your days and weeks accordingly by incorporating EVERYTHING you need to do each day including WRITING, kids, cleaning, teaching, leisure time in front of movie to de-stress, meal prep, play with kids, EVERYTHING so you know where you REALLY WILL designate your time to write. If your calendar says you're writing for 3 hours from noon to 3:00pm on a certain day, DO IT. It's just as important as all your other scheduled obligations. If you have scheduled in all your other obligations, there is no reason to skip your designated writing zone.
That's what I do. Good luck! I so often wish I had no interests aside from parenting, because watching the kids is a piece of cake, it's the other pursuits that tend to get squeezed out if you're not careful. I used to wait until I had "creative inspiration" to work, and realized, my schedule would NEVER fall in to place, and I got NOTHING done. Once I started scheduling a couple of hours here and there, I started getting a LOT of painting and writing done, and I figured out more windows of opportunity than I thought were possible. It takes discipline to schedule creative things, but it works.