I am sorry to learn of this situation. Unfortunately, as a minor, you are still subject to your parents (your mother's) control and custody.
There are two possible options to stop this:
The first - and most effective - is for your grandparents to apply for a legal guardianship over you. This simply allows them to make legal decisions on your behalf (and likely formalizes whatever relationship they have with you now).
You can find information on FL Guardianships here: http://www.flcourts.org/resources-and-services/family-courts/guardianship.stml
The second - and more difficult standard - is for you to apply to the court for an "emancipation."
The age of majority
in Florida is eighteen. In order to seek a court mandated emancipation, minors must submit a statement of "character, habits, income, and mental capacity for business, and an explanation of how the needs of the minor with respect to food, shelter, clothing, medical care, and other necessities will be met." In addition, minors must state whether they are party to any court action taking place in Florida or another state. Minors must also submit a statement explaining why they seek an order of emancipation. Parents must be notified of any such proceeding.
The court then asks for any additional evidence to determine if the decree of emancipation is in the minors'best interest. If the order of emancipation is granted, the minor will have all of the rights, responsibilities, and privileges of anyone who has reached the age of majority (eighteen years of age).