every time she accuses me of "not wanting to spend time with her"

That's the truth. You don't want to spend time with her. And there's nothing wrong with that. Boundaries are important. Me time is necessary, to reload, to get energy, to get some space and to realign with only yourself.

Sometimes when entering relationships, hobbies are seen as 'things of the past'. Stuff that happened to amuse oneself til THE ONE came by and consumed everything. And that's pretty unhealthy and how you end up with people who only watch tv together and wonder why their relationship is boring.

You'll have to explain to your GF that your hobbies are things of now. Make a schedule for you, when do you have time and how much and talk. She seems lonely, so that time is needed for her to make new friends and discover new things about herself. She's in a very vulnerable position, her job and her relationship are bound together, maybe she feels she has to appease you.

Perhaps ask your dad to have her on a different shift, but only after talking to her. Talk to her a few times about what you need, but if she doesn't get it, perhaps it's time to move on.