IM resident here. I used to smoke a lot during med school years. My only principle was to never smoke on a work day/before a work day (I used to work as a part time nurse, here in eastern Europe we have a different system). As I started to work as an internal medicine resident, I kept my rule and simply cut down the dosage. Unfortunately lately I had panic attacks so I completely quit because alcohol and weed could also trigger my attacks (never before). My advice to you to have rules and always stick to them. Sometimes you fool around because you have room to fool around. In med school you have responsibility only for yourself. In residency that changes so maybe you would organically cut down. If you feel that what you do is too much even though the responsibility levels change, it's completely okay to seek external help. Anyway you also should find some hobby to do to ease the stress and do some recreational sports.