I completely understand what you are going through-I am 27 and got sober this year at 27. I have gone through in the beginning of my sobriety, the low period-of realizing the mistakes I made, the doors I have closed, and the damage I have done to my body. But, this is a part of recovery-learn from it, and move on. Also, use your memory in a positive way-respect what you have learned to help you in the future. Weigh the pros and the cons of your new life choice when you feel tempted. I was releived to read your post because after the tough times at the beginning 30-40 days of my sobriety, I felt great for a while after. Now, suddenly at 104 days, I am back to feeling awful about my past. But, I have been learning that those feelings are my alcoholic mind coming back to haunt me again-they are not helpful thoughts. Someoe mentioned above to ask your higher power to take away those thoughts-and I think that advice is rock solid. I have tried it and it worked for me.
Hang in there and remember-things can only get better. My worst days in sobriety are 10 times better than my best days of drkinking. Things only get better from here. There will be hard times-but stay strong, ask for help and the good times will come back to you.
All the best