I didn't have time to miss you when I was double studying med school
That is unfortunate. Did you do anything buy study?
No, I was so busy
It is good to prioritize your studies for something important. It might be a bit kinder to tell the other person if you were away you missed them some.
I didn't have time to miss them and it was much more important for me to get top grades.
I can understand your situation. Sometimes we do not have time for relationships and that is okay. We can put our studies first and then have a relationship when we have more time and effort to devote to it.