I did not initiate FMLA when the back condition started because I wanted to save it in case I did have surgery (now I know I do). I have taken a lot off time off already for doctor appointments and treatment. I have worked for this company over a year. Ok but your employer is obligated to identify absences that fall under the FMLA; they may already have attributed some or all of your absence time to your FMLA entitlement.
Can I be fired for initiating an FMLA leave? Not lawfully.
Can I be fired for the past time I've taken off for doctor visits? See above. You CAN be fired for being excessively absent - even if your absent for valid reasons - but you can't be fired for absences that qualify for FMLA.
Can my employer fire me because my "productivity is low" as a result of the absences for doctor visits? Not enough info to go on. You can be fired for poor job performance; you can't be held accountable for work that didn't get done because you are on FMLA.

