Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.

Which is really sweet of her.
Your job isn't really to find what she asks you to do necessary or fulfilling. Your job is to do it often enough to realise why it's important. It is important. Okay? Just not to you personally. But your job is important to you even though you think it's not a priority, because without it you wouldn't be able to study.
So it's a necessary evil for you. and you do have to prioritise it.
I have to ask why one extra hour a day is impacting so severely on your ability to do this other study. And if it is - then you need to front up to your boss and explain that you are studying, and you need to see if she will allow you (be obedient and respectful) to reduce hours at all, to accommodate that study. Press upon her the fact that if she truly needs you doing those 6 hrs you will of course do them, no question. But if she might be able to see her way clear to reducing them at all, that would be very much appreciated.
Also maybe there's some compromise. a longer lunch break in the middle? Studying at your desk when there are no customers? Don't ask, don't get.
I do find my job important and fulfilling, I just don't find the busy work of flipping through old scripts to find semantic errors that it's too late to fix anyway important or fulfilling.
Where I am from, for part time especially, your place of work schedules you based on your availability. I could easily switch to a different department of the grocery store and do 25 hours, but I really do enjoy the pharmacy and feel that 25 hours (the amount agreed upon when I started) should be sufficient.
Did I mention she never even asked if she could increase my hours? Honestly, she has no respect for anyone else's time in general, including customers. It's infuriating.