My girlfriend (24f) has been getting mad at me (26m)

I just started a new job that’s very stressful a week ago. I have to get up at 4 AM every day and work 9-12 hours a shift 5x a week while training. She hasn’t been texting me much, and she got mad at me after a 12 hour day started at 4 AM because I went home at 9pm to sleep cause I was tired. She told me after I left that she was upset with me and her feeling have been off.

I made time 3 times this week to see her anyways, even though I had to leave earlier than usual at 7pm in order to sleep. (She also lives 30min away, so the drive is long). She was busy other days with her mom, so we couldn’t see each other + I have physical therapy after work 2x a week right now right before I go to bed.

Before this, we used to hang out till 2 AM for hours and cuddle, and we’d call every night for hours. I can’t do that anymore because I won’t sleep well since I have insomnia and need to start going to bed at 7-8 in order to fall asleep on time. We also hung out a ton for over 2 weeks because I had a few weeks off. I tried to get in as much time as possible and let her know in advance that this job is gonna change how much we see each other.

I can’t even get a good morning back most days now, and I’m stressed out about my job and relationship, and I’ve been having horrible nightmares and it’s killing my mood everyday.

How can I do better to be better in the relationship?

( I also expressed myself to her, and she was understanding to an extent, but I don’t think it was enough).