As always, feel free to completely disregard this post since I'm not a parent.
Is there anything specific that you can pinpoint that takes away from the time that you wish you were spending with him? Like, can you pay the bills when he's in bed/at school? Or run all the errands one day a week when he's in school so that you don't have to worry about it a ton once he gets home? Would meal planning help at all (less stress about what to eat/cook for dinner every night)? Is there a favorite tv show one night a week that you could watch together?
Maybe instead of making it a Ce Day, you could do a little bit here and there. If he wants to play dino's, set the timer for 30 minutes and do it. You feel better knowing you made time for him, and he's happy that you played with him. Sometimes it's the little things. Like, I know my Dad came to, and did tons of my sports events when I was growing up, but I also remember that every week he and I would watch Star Trek (or that water world sort of one with the submarine that I can NEVER remember the name of, or whatever other show) together. We didn't do a TON of stuff together ALL THE TIME, but I specifically remember that we would sit down and watch that show together, and it's was really nice. You can't do EVERYTHING, but everything you CAN do is filled with love, and Ce knows that.