Jim, you're sucking up the bullshit from this site.
I reported what the Europeans are saying right now. I didn't say anything about validity. The Europeans are saying the 180/270/360 based on their best guesses and that was before they even thought about boosters. They recently reduced the validity of the PCR test from 72 to 48 hours and the antigen test from 48 to 24 hours.
These are clearly not absolutes. The only thing that is an absolute is that the vaccination works.
One of the Austrian political parties is somewhere between neutral on vaccinations and anti-vax. The other party set up a tent to vaccinate those that wanted to get vaccinated but didn't want to admit it - apparently there was a significant amount of takers amongst those "almost anti-vaxxers"
Action in front of the National Council - "Secret Vaccination Centre": JVP frotzelt Freedom Party | krone.at
"protection" (isn't really 100%, but will most likely keep you from ending up in hospital or dying) obviously isn't the same for everyone. Each person's immune system is different, so each person will have different "protection".
Given your medical history and your social habits (out and about in medical environments), you should ask your doctor if there are any reasons not to get the booster.
I got the booster two weeks ago and aside from having 7G phone reception, everything else is the same. I was tired for a day after the shot, so get it on a day when you're off the next day.