Oh boy. I totally understand. I have been on psych meds for over 10 years and when I turned 30, I started to gain a TON of weight and no matter what I do, I can't lose it.

However, my p-doc says part of it is attributed to medication and its interaction with my changing metabolism and body (as I got older)

Have you had your thyroid checked? That would be my first suggestion, because hypothyroidism can cause weight gain.
Also, please don't listen to your p-doc. You can simply google those medications and find information about weight gain as a side effect in some of them.

The other issue - have you started drinking more? Sometimes these medications cause thirst and people start drinking more, high-caloried drinks.

I wish I had some better advice. But it sucks.
There have even been class action lawsuits against some meds because of the weight gain and increased risk of Type 2 diabetes. But the p-docs are very quiet about that.