Hi Chloe
I am no expert but let me share a few things that helped me and also make a few observations.
Firstly you are overwhelmingly unlikely to drop dead in your sleep. Firstly it doesn't happen half as often as the media would lead you to believe (after all just walking the streets happily is hardly newsworthy is it). Also statistically speaking you are far more likely to get hit by a car but funnily that isn't a messy end that people with HA worry about.
Life is full of uncertainty and the first step in recovery in my experience is to accept that you can't control everything. Mindfulness is a good tool to support this.
The second thing that I found useful in making progress (you will note that idont use the word recovery) is to not view getting better in absolute terms, it is about positive progress over time and that will have peaks and troughs. That allows you not to beat yourself up every time things go wrong - and they will.
Thirdly - make a plan. Being successful at anything requires a strategy and I believe that recovering from an anxiety disorder is no different. My plan was to find a GP that I trusted and could get on with (you are allowe to choose you know), visit them on a six weekly basis which was long enough to push myself, but short enough that I could save my symptoms. Then I insisted that they didn't refer me for tests for reassurance, only if they objectively thought that it would be helpful.
Then I paid for a course of CBT. It wasn't the golden bullet but it helped me intellectualise what I was feeling and think about it differently.
Finally I cut myself some slack. I am a highly strung person by nature and needed to learn to chill out.
I am sure there is more, but I have had to reply quickly before sleep as I am on an early train to London in the morning, but I wanted to reply to your post.
Above all remember one thing. The chances of you suffering from something sinister is overwhelmingly low. You are absolutely suffering from anxiety, so spend at least as much time tackling that as worrying about physical symptoms, or my thoughts are that you are on a hiding to nothing.
Everyone is different, and critically you will find that everyone on here has slightly different views as to what it takes to get better. Equally everyone here is at different stages in their journey towards recovery. I think you need to take the wealth of input that you will get on here and pick and choose what works for you. A big point thought is that people don't typically recover from anxiety by doing nothing.
Good luck and any questions just ask.