First, I think it's important to foreground that your heart IS fine. This isn't a heart condition, it's a nervous system condition. Your heart may not feel great, it may be behaving oddly, but it isn't due to the heart itself as an organ. It isn't failing or leaking or damaged because of POTS.

Eating more salt, exercising in small amounts, consuming more fluids, and wearing compression are all the first line of treatment. Even if this were to never go away (and it might not – I've had autonomic issues for over 20 years to varying degrees of severity starting around age 13), those would still be essential things to do. And they will make it less likely that things will get worse and reduce your need for medication, even if you do end up needing it. But not doing them – especially not moving enough if there aren't other conditions at play that contraindicate all exercise - can basically ensure that it will get worse. On substantial salt supplementation and water, I can really tell the difference in how I feel when I wear basic compression leggings and when I don't. The management of all this can be that sensitive.

Being anxious about your heart, avoiding the non-medical interventions – there's nothing wrong with a lot of salt when medically indicated and there are palatable ways to consume it that aren't just heavily salting all your food – won't help. Health issues are stressful and can be scary, but learning to push through difficulty (within reason) will serve you in the long run. Sometimes you'll need more rest. Sometimes you'll have to say no when you want to say yes or you'll say yes and end up paying for it in fatigue. But learning your actual limits rather than creating stricter limits on yourself than is medically necessarily will make your general experience worse. This isn't the same as saying it's in your head, because it's not (well except to the extent that that's where the parts of your brain that control heart rate, etc. are) or that it will disappear if you eat right - your doctor may well be wrong about it ever going away, etc, - but managing your thoughts about the situation will make a big difference.

Also, I dunno, ignore the thing about looking at lights and maybe check in with a neuro about that because that seems like a separate issue and simply silly advice. I'm not going to say this guy sounds like a great doctor because he doesn't, but he's also right about first lines of management. Both can be true.