You should ask for a referral to a cardiologist and then ask for a tilt table test to either diagnose or rule out POTS.

Talk to your primary care doctor about getting a tilt table test, and that you faint a lot. My regular doctor ordered the test for me, so no visits to extra doctors

Everything that’s already been mentioned but also make sure to include that the symptoms have been interfering with your life and functioning.

I would actually recommend trying to get referred to a neurologist because it is an auto immune disorder, and it should be tracked by someone who can properly manage your immune system as well as show you how to properly maintain your body chemistry when it comes to water, salt, electrolytes… I’ve been to multiple cardiologists, and they have never wanted to take on POTS because they don’t see it as a ‘problem they handle’

Keep detailed notes of your symptoms; what you were doing before/after, what did you feel, how did they resolve, things like that. I have a few different conditions aswell, I've found the best thing is to basically "chart" on yourself and show them. Also helps if you are able to have someone with you at appointments to help advocate for you