I had a similar problem - always recovered well but 18 months ago failed to recover after a simple 6-week, 300mg/week test prop course. I ran 2-3 PCTs with SERMS and tried a low dose AI none instigated a recovery for me.
Eventually I went back and did an 8-week course of testosterone and ran a 'power pct' at the end of the course - this worked. It is now 6-months since PCT completed and I am well, no problems, excellent drive, libido etc. Needless to say my days of AAS use are over (42 years old).
The PCT I ran - 12 shots of hCG at 1500iu, every other day. This commenced 3 weeks after my last test E shot. On the same day I started hCG I began nolva at 20mg a day, this was run at this dose for 40 days and then tapered slowly over 3-4 weeks. I ran clomid for 28 days, 100mg a day for 7-days then at 50mg a day.
I understand the implications put forward on this board regarding high dose hCG BUT THIS WORKED FOR ME. Like you I was about to commence TRT so this was a last option - nothing to lose.
During the PCT I also ran high dose vitamin D, fish oils, D-aspartic acid. I ensured fat was high in diet, calories more than adequate and I cut back on training to total body work plus caridio at 3-sessions per week
I believe that the short testosterone course prior to my my pct aided recovery. It showed me I could function normally again if all else failed and my worse case scenario was a couple of injections per week and not a lifetime without sex drive and ED! This removed an enormous weight from my shoulders and I am sure that the stress and worry about recovery/life without testosterone can be a major factor in preventing recovery.