Bass, I too struggle with depression and have for the past 19 years. Like you, I spent quite a bit of that time period in a stoned haze until I was about 25-26 at which time I stopped almost completely. About once a year or so I would occasionally imbibe with friends, but other than that I stepped away from Mary Jane. To be honest it didn't make a difference in how I dealt with depression other than I became more aggressive and quick to anger. This change lead my wife to strongly suggest I see a doc and see if medications were something I should be on or if there were other potential options for me. I was very adamant about not wanting to go on prozac or any of that type of drug and having to rely on it the rest of my life, but one day I gave in and went to the Dr.
Other than medication there are a multitude of treatment options. One of the best for me was to exercise rather than be a couch potato, playing video games and watching tv all day. I got into a kick boxing class and the ability to literally beat the stuffing out of something for an hour a day is very soothing. Yoga and meditation are two other relaxing activities I have taken up, both of which greatly aid in refocusing my mind and allowing me to maintain control over my emotions/mood. The biggest factor that I have noticed is making sure that I get plenty of sleep. If I am at all tired I am very susceptible to falling into the pit of despair.
Unfortunately for me all of that wasn't quite enough to fully get me to where I needed to be mentally during the winter months so I am now on a low dose of prozac.
There are other options out there such as behavioral therapy, or simply talking with a therapist. It is hard to go it alone in this world, luckily you don't have to. Reaching out, even in such a way as this, is a great start, but you won't get anywhere until you put your feet on the ground and do something about it.
Best of luck in dealing with your situation and if I can be of any help to you let me know.