Particularly since you are not comfortable with your new boss, I would suggest you work directly with your HR manager or your benefits' manager. I have always held my mental health problems pretty close to the vest. Because of the stigma still associated with it, it's on a need to know basis. People are not always as they appear to be, so be careful.

I, too, needed to use my FMLA for a breakdown and then returned to work on a part-time basis which also used up the remainder of my FMLA. Because I am considered disabled (by my pdoc and under the government guidelines) I was able to get a letter from my pdoc requesting accommodations for my disability and because they were reasonable for my position they were granted. Even with these accommodations, I didn't tell my manager or HR manager (both very dysfunctional) why I needed them - only my benefits' manager knew and she was not allowed under HIPAA to discuss any of this with anyone without my written permission.

You should ask your pdoc for a letter explaining what accommodations you need, and also find out if you are considered disabled. Then it is up to your employer to determine if the accommodations you are asking for are reasonable. If they are, then your employer is required to accommodate them.

I think the one drawback is your need for days off is not consistent which could make the accommodation more difficult. I had specific days I took off, but I had to fight for my "no overnight travel" restriction. I was able to reference my interview with my manager where he said several times that travel would be minimal.

Regarding using your vacation time, each employer has their own policies with respect to how it is used in these circumstances. Whether they grant you your request has to be consistent with how they administer their policy. If they allow just one person to deviate they can find themselves in a hot mess when others ask for the same.

I wish you the best of luck with this. I know how hard it is on those days.