Grief hitting hard and at the most unexpected time

My dad passed away suddenly last year, and just when I thought I was starting to feel "okay", I got hit with a huge wave of grief in the last few days. I had just gotten home from a long and amazing vacation with my close friends; I was truly so happy and relaxed, but the moment I got home and unpacked, I immediately thought about how I would never get the chance to tell my dad about my vacation or show him the pictures I took, and I started to cry uncontrollably.

For three nights in a row, I cried myself to sleep, looking at old photos and watching videos just to hear his voice. I fell apart completely when I scrolled through my phone history and found my very last call from him on his cell phone -- it was on my birthday last year. I still remember it was a very short call, but he wanted to make sure he told me happy birthday, and that he didn't want to bother me too much since I was about to make dinner.

I miss my dad so much. When is it supposed to get easier? There were so many things I regret not doing with him, not saying to him... I didn't even get one last hug because he passed away in the middle of the night. I just wish I could talk to him one more time and tell him everything I never got to tell him.