Legal Question in Immigration Law in United States

If your parents are green card holders, they can petition you only if you are unmarried. Assuming you are unmarried, the current wait is about 6-7 years (even longer for nationals of Mexico and the Philippines), but that's just an estimate. You can find the State Department's visa bulletin listing the current priority dates for each family preference category here: http://travel.state.gov/content/visas/en/law-and-policy/bulletin/2016/visa-bulletin-for-december-2015.html

Are your parents eligible to apply for naturalization? If yes, this may provide a faster route for you. From what you mention there may be more options available to you.