My experience with Marijuana

Well, I mainly came here to tell my story to get some opinions, I'm sure something on this level has been discussed before, but I figure coming here would be the best place to come and get some opinions on what's going on with me.

I started smoking weed about 2 years ago, I travelled to PEI, and got some weed from a friend when I was in the province, and took it home and got high for the first time with my friend. After about 3 grams of weed hot boxed, I was out of my mind high, one of the best high experiences for me ever. Over the next year, I smoked weed anywhere between once a month to twice a week, depending on the time of year. I felt completely normal, just got high, had a blast, went to sleep, woke up feeling fine. I got hired to work at a factory last summer, needless to say there was a fair amount of drug use at the factory due to the same repetitive task done over and over, only thing you were allowed to do over a 12 hour backshift was listen to music through a stereo system, earbuds were banned due to safety conserns. The most popular drug there, largely, was weed, which I did occasionally.

I fell into peer pressure one night, and got high during work hours. As far as I can remember, I was about a 6-7/10. I was pretty high. One day a week, turned into 2 days a week. 2 turned into 4, and then 4 times a night, 4 days a week. This continued for about 2.5-3 months, before I eventually left because I hated working there. One night during work, I believe it was 2 days before Christmas break, depression began to strike. I was depressed like no other time before in my life, upset for no reason, loving family, a steady job, but one night I almost pulled a hook blade across my throat during work hours, I still think of that as one of my lowest lows. I couldn't figure out why I was so depressed, until I left, and stopped smoking weed so much. I realized I was depressed because of it, and I haven't felt the same since all of this. I can't put a finger on it, but I just feel like I have a constant haze over my thoughts and sight. Some days are worse than others, some days I feel great, but most days I feel like I lost myself smoking weed every day. Since then I've cut it back to about once or twice every 2 weeks, now I use a vaporizer instead though. MFLB works wonders.

I know I broke 4 no-no's, and I'm wondering if this is attributed to that or not:
-Being 18
-Smoking weed every day
-Smoking weed several times a day
-Smoking it instead of vaporizing it.

Could those factors attribute to the uncanny feeling I have? I feel like there's always something wrong in my head, but I feel like the damage that's been done is done. It could have even been laced with somethin', but it's doubtful. I usually look at it to make sure it has nothing on it that looks suspicious.

I'm looking for some advice, what should I do? Will this haze improve? Will it ever go away? What is it that I'm feeling if the only thing that ever changed was my weed intake, and I've read here and there that cannabis is related to depression.