I won't sugar coat it, I am in recovery for several addictions and it wasn't easy. It is a life long process done one day at a time.
Remember normal people don't do drugs at all because they are illegal, expensive, and dangerous. There is nothing normal or okay about doing drugs a little bit.
I didn't think of quitting until I hit an emotional & financial bottom. People's rock bottom experiences are different. Some are physical (HIV, pancreatitis). Some are legal (DUI, busted copping drugs, stealing narcs, or busted by DEA for abusing prescription privleges). Some consquences are personal (lose lover, spouse, friends). Your addiction will drain you dry until you surrender and ask for help.
I can tell by your post that you know you have a problem. Good for you to be out of denial. If you don't think you have a problem, quit cold turkey for 30 days. If you don't have a problem, quitting will be a snap. If you do have a problem, you will definitely know it.
Check out AA or NA meetings and consider going to rehab. Rehab has helped a lot of people. However, recovery is a lifelong process. And while recovery is really hard, it is really fun. There is a lot of laughter in recovery.
There are lots of recovering MDs out there and they are excellent doctors and fine human beings. You'll meet some in the rooms of AA and NA. There are also med students in recovery and don't worry nobody will rat you out. That's why they are called anonymous programs.
Please choose recovery because if you don't you will never realize your dreams. Good luck.