not being able to take off work for dr.s appt.

I was informed at work that I take to many hours out of my schedule for mental health doctor appts for myself and my daughter. I have bi-polar, anxiety, addictive behaviors. My daughter has ADD & OCD. We both have mental health counseling and mental health dr appts.

I always bring in the dr. appt card when I make the appt. My manager knows in advice when I have them and I bring in a paper when I return to state that was where I was.

I make up my hours or I take them hours without pay.

My question is..since we both have mental disorders can my employer tell me that I can not take the time off for my appts? I work full-time and I only have four hours on Fridays to make all these appt. I am an at-will employee but have been employeed with them for 11 years. Thank you for answering my question.