hiya hun trust me i can make my heart rate go fast just by thinking about it, i think some chill time is in order for you :-)
Don't make me come over there. Everything -EVERYTHING- is in our heads, at least in terms of what we think and feel. And because of that, what we are thinking and feeling -even if hidden from us, has MUCH to do with the phsyical symptoms: tail wags dog -badda-bing!
I don't know how that bath and double water thing works, but it WORKS. But here's the main thing: you have seen that your heart rate can respond to a more "normal" pace. Somehow, you DID it, and that's way cool.
So NOW, if ever there was a reason to stop checking -you've got the reason. Give yourself a vacation from it -you've earned it!