I missed the part where you had Achilles tendon surgery - welcome to the club. (I realize admission was involuntary.) How long ago was it?
I did very little for 3 months after my repair - just like the doc told me. PT was a female dog with a bad disposition and very sharp teeth... but chased me in the right direction.
The treatment that felt the best was ultrasound & localized massage. That really seemed to loosen the area up, which made everything feel better. Unfortunately, they did that before the PT, i.e., they undid their fine work immediately after.
Also unfortunately, US and massage weren't things I could do myself.
My advice would be to find that balance between therapeutic pushing the limits and stopping short of set backs to the healing process. Guess what? Your pain is your measuring stick. Listen to your Doc & PT's, but adjust their instructions to your needs (assuming you maintain an attitude of wanting to get back as close to 100% as you possibly can). If one goes wimpy, one will not recover what one might; if one goes macho, one will prolong the process... and re-injure... and probably not recover what one might.
Only you can find that sweet spot. You do that by making the pain your friend (frenemy?). Learn its language and listen to what it's telling you.
Hm... since this is a gun forum (and so much more![TM]), I'll apply this analogy:
You got a new gun. There is no shortage of experts to tell you exactly what is best for acheiving ultimate accuracy therefrom. Some will say theirs is the ONLY thing and you're a fool to not listen. But the bottom line is, you have to work up/find the load that shoots best in your gun. You have to find/develop the grip+stance+sight alignment+trigger control combination that allows YOU to shoot THAT gun as effectively as possible. Ultimately, YOU have to decide if you really want that and YOU have to be disciplined enough to pursue that and YOU have to know YOUR limits and work with what you got.
It's the same with PT.
Best wishes for a speedy and complete recovery!