I think that Dreamer X didn't understand your situation. Let me know if I got it right:
Your parents are non-US citizens and they also don't have a Green Card. They are legal in the US on a work visa and you are dependent on their visa so when you are 21 you will have to leave the country. Because you are dependent on their visa you are not allowed to work and that's why you don't have a SSN.

I think that it's 5 years after getting a work permit that you can get a Green Card, when was your visa issued?

You are in the US legally so you don't qualify for the DREAM Act. I'm not an immigration lawyer but I know that if you leave the US before your visa is over - you parents could sponsor you when they'll get their Green Card, the problem is that that I think it will take at least 6 years because there's a huge waiting list if you're over 21.

Or you could always meet someone and get married, because you entered legally - you will be able to get a SSN by 2-3 months and a green card few months after that. This is your best option.