Marry an American or get another job that will sponsor you for your greencard, these are the only options, a good thing to try is ask the school you are now working for if they can get you a H1 visa, this may be possible because at the moment the only place there is a genuine shortage of pilots is flight instructing, If they get you a H1 visa begin your quest for a green card (actually pink) right away, it takes about two years. Go see an immigration attorney before you do anything, they are not that expensive.