Getting married at 16 is not very smart. Been together for 3 years? That's not long at all, especially since it's only been two years since you got back together. At 16 and 17, there's no way you can earn money enough for a family. You have to get a house/apartment, pay for food, gas, taxes, etc. At 17, you can work a maximum of 20 hours a week during the school year. Do you think your husband can support you on a part-time job while going through high school? Or do you want him to drop out and get a full-time job so he can pay for you? As a high school dropout, he would have almost no chance at any decent-paying job. Go through college first, so that you or he can get a well-paying job so that you don't go bankrupt the first year you're married.
Have you ever tried living together? I'm guessing you see each other in school, go over each other's houses, but have you ever lived with him for an extended period of time?
Also, as newlyweds, you're probably going to be having sex. If you become pregnant, you'll have to have an abortion or drop out of school. If your husband already dropped out to get a job, and you drop out to take care of the baby, neither of you gets a full high school education, meaning neither of you can get any good jobs, which means you'll live on minimum wage. Is that really what you want? If it is, go ahead and get married. If not, wait until your husband (and/or you) has a stable, fairly well-paying job and you've both graduated at least high school, if not college.