Hello yakmom: Well... you're not old to the Skeezyks!

(68)

From what you wrote, I take it you've been, perhaps, a primary caregiver for a quite elderly person for several years now. This can be wearing in-&-of itself. Plus you have your own issues.
Setting boundaries is a great idea in theory. In fact, I often suggest to members, here on PC, whose threads I reply to that they need to learn to establish & enforce boundaries.

But it's one thing to say it (as your therapist did.) It's quite another thing to actually do it & make it stick in a real life situation.
Yes, perhaps some adjustment in your med's is called for. But it sounds to me as though you're simply burning out. And trying to mask that by changing or increasing your med's isn't really going to solve anything, in my opinion.
All you can do, is all you can do. And it sounds like that's what you've been doing for the past 5 or 6 years. So I hope that, in some way, you can prevail upon the sons & daughter to finally give you some consideration & make the difficult decisions that need to be made. I wish you well...