Oh I have been there, too! Supervising people older than me. I totally felt like an impostor. It was actually not a great experience and I was sort of picked on, although not really by the people I directly supervised, more like the other people I dealt with and my supervisors. I thought at the time I just didn't have the skills and was too sensitive, but in retrospect the problem was not really just with me. TheSeaCat hang in there!

Glad your heartrate is better. I have mild tachycardia from clozapine and it's annoying. I'm glad it isn't worse.

Being young and in authority can be really hard or really funny. At my first post-master's job I was supervising 3 or 4 people who were 5-10 years older than me. I'd been there a while when my assistant got a phone call for "that girl who helps out in therapy". He laughed and laughed explaining I was his supervisor. I also once had a patient tell me "You are 12 and you may NOT tell me what to do". (I was 25 but looked young). I had to have an assistant sit there and I'd tell the assistant what I needed and she'd get the patient to do it and I'd make a note then repeat. It was funny but sometimes got old in those first years. I guess try to laugh as much as you can and ignore the rest.