The reality is, nobody can tell you for sure what will happen to you.

But try this on for size... most healthy men will regain their normal testosterone production upon cessation of TRT. This can happen after 11 months (such as your case) or 2 years or even 11 years. So, that should offer some insight into the fact that your TRT is unlikely to be doing any sort of permanent damage to your ability to produce testosterone. There's never a guarantee in medicine, but I would certainly bet that there is no "point of no return" where HCG would have no effect on an otherwise healthy man.

Of course, if you were on TRT for 50 years and now you're 80 years old then it is very reasonable to think your body has aged and things simply won't work as they used to due to normal aging. In that case, one's response to an LH analog might very well be nil. The plus side would be that you just continue with the TRT lol.