Well I can see how not even being able to visit friends or have any over could contribute to those feelings, isolation is not exactly healthy. Are you in any sort of treatment now or seeing a therapist or anything? If so you could tell them how you are feeling perhaps there is help available. Sounds like your parents could use some therapy too though, but not sure they'd listen to you if you tell them that, but might help them deal with the situation better and be more understanding of where you are coming from.

Either way sounds very frustrating, sorry you are having to go through that..sounds like this current state of affairs is doing you more harm than the weed, but that's just my opinion. But if you are 17 that almost makes you 18, at the age of 18 your parents wont have as much authority...unfortunately they can 'kick you out' if they decide to some parents use that to try and enforce 'rules'. But yeah if you're really feeling like hurting yourself or anyone else now, then you need to address that immediately and then deal with the other stuff once you're a bit more stable. Not judging though I've been suicidal multiple times and have had to go to the ER, but glad I did after the fact even if going to hospitals isn't the most pleasant thing.