You are allowed, and deserve, to spend time you might have to yourself, during your days, to spend time on things that you enjoy and will help you relax. Including hobbies. You need to take yourself into account, or you risk burning out. I know that you have 'unscheduled' time in which you will allow yourself time to do things things, and that is great. I don't think it is fair for you to schedule other necessary things, like grocery shopping and car repairs into the time you set aside for yourself. At the very least, I think you need to try and not feel guilty about filling up slots in those unscheduled periods with things like an hour or two of writing or knitting or internetting or other 'hobbies, and if you do schedule them, you need to to treat it as firmly as any other commitment.

You have to be fair to yourself, as well as the other people in your life.