First, good for you for making several substantial changes, what with the move, job change, and school. And it's hard to enforce good boundaries with needy / aging parents and have an adult-to-adult relationship when there are habits of co-dependence and manipulative guilt going on, as seem to be happening in your case.
As an adult, you do deserve to take time for yourself. And you don't need her permission. But I know it's not easy to assert boundaries with parents.
A couple of suggestions you might think about --
If there is a college or university program in social work, counseling, or clinical psychology, see if they have free or low cost sessions with student-counselors. Get some support and strategies for setting and holding boundaries with mom.
If possible tell mom you need to discuss a mutually workable arrangement for your help, including going along to her appointments. See if you can make the appointments for her so they fit your schedule. That could help eliminate one of the big irritations in your current interactions.
Good luck!