I've been in a similar situation before when working in a different state for 4-5 months of the year.

It took me two tries, but I found a primary care doctor who was willing to see me. Since you're only on one antidepressant medication, I don't see why a primary care doctor couldn't manage it, unless you just want to have a psychiatrist do it.

Even another psychiatrist might be a better option. I cannot think of a single good reason why a provider would need to see you every two months if you're stable on a simple one-antidepressant regimen. Sounds like they're seeing cash dollar signs.

I don't know if having your out of state provider send a 3-month prescription to a mail order pharmacy would be a workable option. You might run into the problem of it having been too long since you'd seen them, although I think technically they'd be able to prescribe 12 months of mirtazapine in most states without seeing you in person, although most would prefer 6 months to be the maximum.

I hope you find a way to work it out. It can be a real pain finding a doctor when you're not in the same location all year.