My doctor doesn’t understand my disability

I have intermittent FMLA for ‘mental health’. I’m autistic, I have cPTSD, and severe anxiety and depression. I have been this way my whole life. I have had suicidal ideation and have self harmed since I was 8 years old. I have learned how to handle things better as an adult, but I still struggle very badly. Having FMLA is the only way I can keep a job. I need days off when I’m too overstimulated or burnt out or I will become suicidal very quickly. I have been in therapy, seen psychiatrists, tried so many medications, it doesn’t get that much better. I still need my fmla no matter what. But each time I go to my doctor to extend my fmla she stresses that I need to ‘actually try to get better’ so that I don’t need it anymore, and keeps saying she won’t continue to approve my fmla. She doesn’t understand that this is my life, this isn’t just some temporary issue. It doesn’t go away. Do I just need to try a different doctor? I don’t want to start over again. And it’s very likely that a new doctor also will not understand.