I had the exact same problem like a week ago and I’m 18, my doctor said I have anxiety too, he also said it’s cause of my lifestyle habits :- waking up late , long gaps between meals. Even though I do have anxiety my heartbeat wasn’t fast because of that, i have an iron deficiency and I had no idea about it till now, I started taking vitamins and it’s gone down to 79 now! It used to be 120 - 130 sometime back. What I can tell you is that either you could have the same problem as me or it could because of only anxiety for you, or it could also be because of
Thyroid dis function
Or anemia (which is the case for me)
Don’t worry too much about it , you’ll be fine!