Laura - it's a challenge if you have to share your computer - but maybe this frees you up to do other things! You want to do photography and drawing, neither of those involve a computer! So in your non-computer times, how about wandering around your yard taking photos of random things, and doing some drawing! Even if it's five minutes, call it your "Five Minute Challenge". That can easily be a "walking meditation". Do a "five minute challenge" drawing where you try to do just one small little thing. Don't worry about big time blocks for now. Enjoy and relish the small ones.
That way you feel like you've made progress, and the times you DO get onto the computer, it's yet another treat in your life
If your family is alive and active at the end of the day - how about the beginning? Is there any way to wake up a half hour early and make that your "special mommy time" when everybody knows you are in your quiet, meditation spot?