I think the biggest problem here shouldn't be your age.

There are Dom/Sub relationships where both parties are intimately close and healthy. Even in a BDSM relationship, I don't think it's right for the Dom to be okay with you harming yourself. There might be punishments set out for you if you are 'out of line', but they should always be talked about and both parties should have full agreement to it. I have never been in this type of relationship but I was always under the notion that for 24/7's to work, there has to be a lot of trust. I was also under the notion that a Dom will listen and try to help the Sub and that the relationship structure is mutual.

It is bull that he uses the 'dynamic' as a reason why he cannot help you or get closer? to you. You can still get a degree in art, and still be highly successful in the work place but come home and be subservient to him. He can make rules, like 'call immediately after work and come straight home' which you can follow after you leave class, but he should be willing to give you space if you have a group project or something. You can work this dynamic and let it allow you two to pursue pretty normal lives outside of the house knowing that when you go home he is your master.

I don't think neglecting someone else's feelings in a loving relationship, no matter the construct, is fair to either person.