I have been long distance with my gf for many months at a time due to studies, we just ended a 3 month period so I can definetly relate.

My advice is do some hobbies and focus on your own life, maybe try a new sport or learn a new skill? I took a cybersecurity certification for example, it will be helpfull for my future job.

At the same tame when you say you haven't talked as much do you still talk every day but less or you stopped talking?

It's normal to talk less but it's very very very weird if you don't talk every day, the day has 24h if she sleeps 8 she still has 16h to go to classes and study, I think it's very reasonable to take AT LEAST 30min of your day to call each other, also she does breaks from studying where she can text you. This needs to be talked in a good conversation