Of course you are depressed..you are 17, sitting in your room alone all the time, smoking pot and playing video games. It's enough to make anyone depressed.
First thing you need to do is go and consult a doctor and get referred to a counsellor. It sounds like you could use someone to talk to about this, so take advantage of therapy sessions. At the very least they will get you out of the house for a bit and interacting with someone.
Then try to start getting some exercise. Exercise releases endorphins, which are your body's natural high. It will get you a bit more fit and healthy, distract you from your worries and make you feel a lot better. It will also help with insomnia, which is a common symptom of depression. Getting some fresh air and a tiny bit of sun can help get you feeling a tiny bit better. Start off small, just going for a walk every day and then try to increase it to something like going for a swim, or a jog or just increasing the length of your walks.
Also, cut out the weed. It is just going to make you lazy and zonked out all the time. It's hard to do anything if you're always stoned.
You're not alone in suffering depression and you aren't going to feel this way forever, but you have to start doing things to help yourself. Part of growing up is learning how to look after yourself and you will feel a lot better if you are doing something to help yourself out. Try to participate in life as much as you can, even if it doesn't feel good. Sometimes you have to do what's right for yourself and wait for the good feelings to come later.
Oh and as for all the ideas which you quickly knocked before they were even suggested. Reconsider those. I bet if you put more effort into it you could go out once a week with some people, or you could find another way to occupy your time. Just because you don't want to go and do these things and they aren't as easy as sitting around, doesn't mean they aren't possible.