Likewise. My semen volume has decreased on HCG. The consistency got thicker as it had become like water though I was expecting a lot more volume or at least what it used to be before TRT. I use pregnyl.My testicles have maintained their size for the past 5 weeks, at least best I can tell. Perhaps it takes longer for them to shrink.
Another unusual surprise is that, after stopping HCG, my semen volume is now back to normal. Which is to say that my semen volume was much less while I was on HCG, and it's now back to a normal amount. I've read many reports of HCG increasing semen volume, so I was surprised here as well.