@mjay8- Welcome to Mayo Clinic Connect. It looks as if you've had a very, very rough time for over a year. You said that you weren't tested early on. Have you since been tested for COVID-19? Did the blood work that you had show any signs of COVID-19? Or for any other illness? Before COVID had you ever had any symptoms like the ones that you have recently suffered?

POTS can be diagnosed using the title-table-test. I strongly suggest that you have this test.
https://my.clevelandclinic.org/health/diagnostics/17043-tilt-table-test
This is a very thorough discussion about COPS and how you can get help. There are also medications that can help:
https://my.clevelandclinic.org/health/diseases/16560-postural-orthostatic-tachycardia-syndrome-pots
Some people who have had COVID-19 have reported that their symptoms lessen after having the vaccine. So this is a good thing.

I also recommend that you contacting VAERS with your symptoms and seek out any help that they can give you.

How to report to VAERSYou can report to VAERS online at https://vaers.hhs.gov/index. For further assistance reporting to VAERS, visit https://vaers.hhs.gov/index or contact VAERS directly at info@VAERS.org or 1-800-822-7967.

Also, you can access Survivor Corps
https://www.survivorcorps.com
Survivor Corps is one of the largest and fastest-growing grassroots movements connecting, supporting, educating, motivating, and mobilizing COVID-19 Survivors. They will help with post covid-care

Merry