PMSelle (I think) said something similar. the mental ones (ocd and SAD) are definitely related. physical ones maybe too. I'm sure I would be more fit and healthy in general if I could fix this as I'd be out more and exercise more.
I'm hoping this time next year I will be on testosterone and be changing all this though
Heart racing can be caused by the stress you are going through indeed.
Go and be brave Soph. If need be, print out some things you have written here over the years on being trans. They'll see it is not something new popping up, but something that has been there and got more and more clear over the years.
They may not change the meds right away. But, taking the hurdle of telling them may be a relief for some of your symptoms already. And, they are medical staff, they are obliged to keep secret what you tell them. Once you tell them, they will have to take you serious on this. And that will make a difference for you I think.