Lovey, I wish I had a cut and dried answer for you. Like Mig and a few others, I tend to really go until I have to stop. If you'll recall, my rheumy made the point a few years ago that I have to learn to pace myself. I know that would go down about as well with you as it did with me.
I'm glad to hear the iritis is under control, but sad to hear that you are back to the same old med. drill. You might want to start practicing some relaxation/meditation techniques, such as progressive relaxation, mindfulness meditation or creative visualization, which have helped many people. Personally, I have trouble with formal relaxation and meditation techniques - my brain just doesn't cooperate. However, put me beside a river or brook, or sit me down under an old Oak with my back against the trunk, in the sun, and just taking in the sights, sounds and smells of nature really helps. One other thing is journalling. Sometimes, just putting it down on paper can help to ease the load somewhat. Gets it out of your psyche, so to speak.
Also, pulling weeds. Honestly, the most cathartic thing I can do when I'm feeling stressed is going out and pulling weeds up by the roots - especially if it's something like Milkweed, or Stinging Nettle, or Cow Vetch, for which the root system is connected like tattered lace. I find tracking the roots as far as I can, so that I get as much as possible of it out of the ground just feels good. Wear gloves, tho. Stinging Nettle HURTS!!!!! Not that I've been stupid enough to try to pull it out of the ground with my bare hands. Nah. Not me. I just leaned on a bunch of it one day, before I learned to recognize it.

Or, if you want, I'll put you on the phone with my sweetie and he'll tell you puns until you're begging him to stop!!!
As for how did you get to be 33 before learning this ... you're learning it alot earlier than some folk I know. There is no set time at which we are supposed to know things, so please don't beat yourself up about this. We learn as the lessons come up and then it's up to us as to whether or not the lesson will stick. You've had no time to learn this lesson what with university, med school, getting married, moving to a whole nother country, retesting for months to practice medicine over there, trying to make a living, getting a job in your chosen field ... Lovey, you've been through so much over the last few years, I doubt you've really had time to sit down and think about this stuff. Now, you need to make the time. Schedule it if you have to, make yourself as important as any of your patients.
Love and hugs,