Hi! Be patient! I was told I had that, but it turned out to be damage to the back of the kneecap - full thickness cracks and all sorts. Gradually stopped doing the things I love because of the pain - skiing, cycling etc. It took 10 years to insidiously creep in, all while I was thinking it was patella femoral. Eventually decided to see a consultant, had an MRI, and that showed up all the damage. In fact it wasn't patella femoral at all, just the pain was the same.
Had surgery last November, have been doing basic rehab, but recently stepped it up with a proper gym routine and it's all coming back ! I can cycle more, I'm hopefully to ski this season, I can do stairs, I can sit on the toilet - all without pain. I regretted the surgery for a while because I thought it had made it worse, but its' getting better !
Still got some tendon and fat pat inflammation and pain which can continue for a couple of years apparently, but it's a good news story otherwise.
So 10 years of pain, gradually giving up what I love, and now on the way to recovery. I'm not saying you're in for 10 years of course !!!!!! Different situation, but I know what it feels like to feel like there's no hope. Start of this year I was miserable - the surgery caused a DVT as well - the knee hurt, I thought I'd made it worse. But it has all got so much better. The gym routine was the turning point (although of course needed the surgery too).
Good luck ! I guess also don't be scared to question the diagnosis, and/or more investigations, and/or a different physio if you feel like you're not making progress.