Eliminating multiple buffers

Right now I buffer with alcohol, marijuana and food. To name a few. I have the thought that the future me would need to believe “I’m not a user” in order to be a person who doesn’t buffer with these things. I used marijuana this morning and now I’m feeling incredible shame from the thoughts “you shouldn’t have done that,” “you didn’t plan for that,” you failed again.” I’ve been working to figure this all out since October and have been successful in reducing alcohol to 4 drinks a week and completely eliminating marijuana. When I added the work on not overeating I did ok and lost 10 pounds. Now I’m back to overdrinking, overeating and overusing marijuana. Suggestions have been to focus on one but they all seem so codependent on each other. One leads to another and so on. Why am I finding it so hard to put it all together? It’s like I’m not willing to let them all go and it’s so painful. But I know I’m capable.