If you went vegan nearly 20 years ago, that would've been around the year 1999. And if you had been vegan for 17 years for a few years after that, let's say 3 years (by saying a few, I assume that is more a couple) then you became a vegan in around 2002. 17 years from that time is 2018/2019. Wow, you're still a vegan.
And wow, the internet and digital camera and record keeping technology have become significantly better since then. Yet you have no personal evidence, whatsoever, apart from an obviously fraudulent story, that you were ever a vegan. No photos of you hanging out with the stinky vegan friends you claimed to have, no photos of you at vegan events, no blood tests, no doctor's reports, nothing.
From https://www.nhs.uk
"GP records should be retained until 10 years after the patient's death or after the patient has permanently left the country, unless they remain in the European Union.
Electronic patient records must not be destroyed or deleted for the foreseeable future."