It sounds like it sucks atm.
Maybe actually shceduling 'time off'? An hour here or there could help, and would even possibly make you more productive at other times, becuase you might feel less cheated of 'free' time.

And at the end of the day, you do have a fuckload on. You're doing a fulltime job, writing a PhD, doing I don't know how many other activities - it is a lot. Some folk do their full time job and just watch TV. Don't beat yourself up over feeling like a headless chicken sometimes.