I guess it's a question of priorities. Sounds like you have just about every minute of the day booked for something. I use to be like this and when I complained, my husband said you only get the time you take for yourself. My daughter said "Mum you set too many things to do and not enough time to do them in.
Took a while but I eventually did it and the world didn't come to an end. I know you can't take time from school or job but can someone else cook dinner and do the dishes at least one night a week. Can someone put the clothes on to wash, vacuum the floors, etc., etc. I'm sure even an hour occasionally would be better than nothing.
I wish you well and hope you are able to take some time for yourself.