How can I show her I can change? 19M, 19F

I (19M) was broken up with a couple of days ago, and it’s been rough. We are both 19 and go to the same college, and started dating a few months before summer break. We live about 2 hours away, and at first, we handled the distance well. Over time, I got too comfortable and wasn’t present as much as I should have been. She was going through a lot of stress this summer, but I was so wrapped up in work and the relationship was so fresh that I thought I was doing enough when that really wasn’t the case.

Fast forward to August, when she broke up with me 2 days after I got back. At the time, it seemed like it came out of nowhere, but thinking and looking back through old texts, there were cries for help that I missed. I am not pinning this on her, and I take full responsibility. She‘s not the type to break up just to get with another guy.

In the days following, I started writing down my thoughts, feelings, and ways I let her down. Before we started dating, she gave me a birthday card with 19 different reasons she loved me. For every one, I wrote down reasons that I could do better. We’re currently giving each other distance, but once we start talking again, what are some ways I can show her and not just tell her I can change?