OP you are completely right to be annoyed and infuriated.
The NHS babies you as though you are 3 years old and unable to interpret any data or anything at all really and should just 'wait to be told what to do' and never ask any questions.
Thank God for the app because without it, I wouldn't have discovered that I had a life-altering disease that NHS trusts locally to me had actually moved the goal posts on, but the app still had the old measures.
You are 100% correct you need to take your health into your own hands as the NHS will literally have you crawling on the floor before they take any action or allow you any kind of proactive interventions at all.
I've found since the age of 45 I've had to become my own doctor because they won't take any of my health issues seriously. Having seen my own DM die of complications, it's driven me to be far more proactive.
I'd ask for all your data, as legally provided for by whatever NHS act provides for it. Ask ChatGPT. What else are they hiding from you?
On another note, with regards to migraines, you could look at the scientific data on vitamin B2 - high dose - to see if this helps you at all. It's not for everyone, only those with MTHFR gene and a certain type but if it works, it's life-changing and you could come off the drug.
Additionally I really recommend the Zoe Nutrition program for lowering cholestrol.
I've been repeatedly fobbed off. Just recently I've had an operation which has cured my condition which would have literally robbed me of good health but on the NHS it's a condition where you 'watch and wait'. I've watched numerous women crumble in a Facebook group waiting for help and they are repeatedly pushed back on again and again and again.
I really don't trust the NHS unless it's for acute issues or terminal diagnosis.
Even then A&E is a shocker and terminal help is also a complete shocker too. It's made me consider moving abroad, the healthcare here is so woefully underfunded.