First, under the FMLA, an employee can only take off up to 12 weeks. Second, an employer can require a certificate from a doctor stating that you require time to recover from your injury. Has your employer requested this certificate?
I would suggest that you ask your doctor for a certificate stating that you require additional time for rehab before returning to work and submit that to your employer. If you encounter any problems or issues, please consult with an attorney.
Zachary Zawarski
www.zawarskilaw.com
You need to consult an employment attorney in your state ASAP. If your Employer has given you all of the FMLA notices it was required to give and you remain out on leave beyond 12 weeks, you might find that you have lost the right under the FMLA to be reinstated to "the same or an equivalent position" to the position you held prior to the leave.
While you may still have a right of reinstatement under state or common law, another federal statute (such as the ADA) or a collective bargaining agreement, no one can tell that based upon the limited facts you have provided. You need to review all of the facts with an attorney in the state in which you work so that he or she can help you determine the answer. DO NOT delay. Consult someone immediately.
Disclaimer: This answer does not establish an attorney-client relationship or constitute legal advice. It is for general informational purposes only.