1) HCG mimics LH, it has very weak but some FSH activity. This may keep some fertile but not others. Also the main role of HCG is to keep Leydig cells working which also serve to nourish Serotoli cells and keep them from atrophying or during.Thus, when FSH is provided the Serotoli cells can starting making sperm
2) Triptorelin is used to chemically casterate males at certain doses.Taking this not under the orders of a doctor who know was they are doing could permanently ruin your HPTA axis and make you infertile.
3) in theory clomid would be of little additional benefit. It works by blocking estrogen from binding to the pituitary and this blocks negative feedback of estrogen causing increased FSH and LH. Androgens If present though will still cause negative feedback and it won’t matter that the clomid is blocking estrogen at the pituitary.
4) some TRT doctors are using FSH or HMG for males on TRT that want to improve sperm production. You could inquire about this. I believe the rule of thumb for sperm production is about 2-3 months so it may take several months of therapy before being tested to see if it works. It’s pretty expensive medication though.
This is a journey that would benefit from having a doctor who knows what they are doing. Especially if you are on a timeline. Be wary of online advise. For example people can really mess themselves up with the wrong dose of triptorelin (self casteration)