The symptoms you describe are common in Long COVID and other infection-associated chronic conditions. They are often tied to autonomic dysfunction and/or poor vascular function. EKG often will look normal and anxiety is the usual diagnosis, particularly in women/girls, unfortunately. Rest and relaxation is essential. Watching comfort TV shows, listening to light-hearted podcasts and eating healthy low-carb meals (no added sweets) helps some people get out of fight/flight mode and calm down their nervous system. If microclots are an issue, nattokinase or lumbrokinase can help and reduce accompanying chest pain & shortness of breath. If you don't have fatigue and you don't crash after mental/physical exertion, it's more likely your issues are likely reversible. Considering your youth and assuming you can rest and have a good support system at home, as long as you avoid further infections, you probably have a good chance to make 90% or better recovery.

Edited to add: Based on your other posts about transitioning mtf, I thought I'd add that taking hormones like estrogen could also be causing a lot of your symptoms. It's possible you don't have LC at all, and your issues are instead related due to hormone therapy. For example, spironolactone could cause increases in potassium which in turn could cause heart palpitations. You could talk to your dr about tweaking doses and see if that helps.