Biological effect of chronic anxiety on the body?

I’ve suffered from chronic anxiety now for 15 years.
Started as debilitating panic attacks and now it’s more hypochondria but a constant sense of unease.

I worry morning and night about a lot of unnecessary things. I’m too old for this I’m 39.

My Dr tells me the body stays in flight and fight mode even when I don’t necessarily have the adrenal effects of anxiety – hence now having IBS, GERD, gastritis and just a feeling of unease a lot of the time. I also get night time anxiety more than anything, waking up in a panic, brain zaps (no drugs) etc.

I am wondering about the biological, neurological implications and mechanics during chronic anxiety.
Does anxiety affect the parasympathetic or the sympathetic nervous system?

Is one needing to calm down or are both out of whack.
Is it about trying to stimulate or under stimulate my vagus?

I can’t just take drugs and that be that.
I’m wanting to understand what is actually happening in my body so I can then work at controlling my anxiety that way.

I believe through understanding the actual biological process re: what hormones are being released etc
I might actually be able to calm the ‘right’ parts of my body down and eventually get back to a normal state of homeostasis!

Does this make sense or is it all just a ridiculous notion?

Thanks!