You know what? There are things that I think it is 100% positively okay to become triggered and upset over - and medical procedures are one of them.
Even so called "normal" people get upset over medical procedures. With our histories, shouldn't we then cut ourselves a little slack here?
I got all just beside myself over an ultrasound of my abdomen looking for gallstones. A shaky teary mess. The technician was like "are you okay?"
Well, obviously not....
It turns out I was just really constipated. THe doctor said "You know this is really good news, nothing to be upset about, some over the counter laxatives and you'll be just fine" He was totally clueless, god bless him.
But I totally hear you about wanting to be better for your T. If I was your T, however, I would be very very proud of you and would want you to be equally proud of yourself.
You may feel the triggers, you make react in old way, BUT you are NOT surrendering to them. You are out there doing what needs to be done and facing them head on. To me, that is a huge victory.
Remember, being brave doesn't mean that you don't feel fear. It means you feel the fear and do it anyway. You are honest about the fear and not letting it control you. It's heroic if you look at it that way.
I hope you can open yourself up to the way I see it, and the way I'm sure your T sees it - a brave woman, fighting a hard battle and winning.