We need to separate spermatogenesis and seminal fluid production. Sperm is produced in the testicle and regulated by gonadotropins (FSH and LH). On the other hand the majority of the semen volume is produced by the seminal vesicles, which is regulated by androgens and not gonadotropins. See below regarding androgens for semen fluid.
Encyclopaedia Britannica says: “ The size and activity of the
seminal vesicles are controlled by hormones. Production of
androgen, the major hormone that influences the growth and activity of the seminal vesicles, begins at puberty and starts to decline at about the age of 30. In the absence of this hormone, the seminal vesicles will degenerate (atrophy).”
“The finding of normal sperm concentrations in two subjects with 5 alpha-reductase-2 deficiency suggests that DHT does not play a major role in spermatogenesis.”
<p>Semen analyses were performed in nine male pseudohermaphrodites with inherited 5 alpha-reductase-2 deficiency and decreased dihydrotestosterone (DHT) production. The semen samples were characterized by extremely low volume (range, < 0.05 to 1.0 mL), increased viscosity, and poor liquefaction...
pubmed.ncbi.nlm.nih.gov
We also seen anecdotes that finasteride causes low semen volume (via lowering DHT which is an androgen), also Proviron causes high semen volume (it’s similar to DHT).
So we can conclude the solution to increase semen fluid volume (via the stimulation of the seminal vesicles) is not gonadotropins but to increase androgens/DHT. To increase sperm itself, you need to increase gonadotropins.
Indeed there are still many shooting small loads after adding HCG and FSH and lots of guys shooting big loads on grams of steroids which provide massive androgen if stimulation. It’s not strictly always the case, there are a few examples in the opposite direction.
But I hope this is a starting point for my hypothesis “Increase DHT to increase semen volume”. This could be via scrotal creams or the addition of masteron/proviron/etc to TRT. Remember this increased volume will still have reduced sperm due to LH and FSH being zero.
Interesting fact: The leaflet for proviron says it will also increase sperm counts and parameters (contrary to logic which says exogenous DHT would surely reduce sperm and related parameters via shutdown). This solution can be used by those not on TRT/who have quit TRT.