Sounds like you're on your way out. I can strongly relate to this in my own way, having survived several years of substance abuse when I was younger. I've lost a lot of people in the past ten years too; some have passed on, others moved away, while others have changed and fallen out. It's interesting to see the word 'speed' used again. That's what we called it back in the day (1970s and 80s) before Breaking Bad, and the word Meth came into the English vocabulary. Good luck, whatever path you choose.

stay away from any drugs that aren't legal for recreational use in the states of colorado and washington. especially from the ones you mentioned. cocaine, and especially speed and ESPECIALLY HEROINm the most addictive substance ever. These substances have never done good for anyone and they aren't going to do good for you.
4 years is a good length of time to hold a job. A large percentage of the white collar work force can't hold a job that long. Absolutely nothing to feel bad about. You already have more going for you than people who can't find work at all.
also, you still have lots of time to meet someone and get married (or have a common law marriage which is probably more your style).
10 years from now you probably have some pretty good looking at your side and a job that pays three times what you are making now. As long as you stay away from the substances that have been mentioned up above.