I assume that your parents somehow legally ratified the decisions that they made. If they agreed to this change, you may not have been aware of any legal paperwork that may have been filed.
By living with your Dad, your Mom probably agreed to give up any child support payment that your Dad was making. (In fact, she may have agreed to pay him some child support.) BTW, if she agreed to this change, what makes you think that she wants you back?
You don't say what state had jurisdiction, although you posted in the FL board. In FL, you don't have the absolute right to choose which parent you want to live with until you are 18. (At that point, you could choose to live with neither parent.)
I know that a 18 months is a long time for a teenager, but, if I were you, I would "deal with it" until you graduate from high school. At that point, you are free to make your own decisions.
If you are having trouble making friends in your new community, you might talk to a school counselor or ask you Dad to arrange for some counseling for you.