My libido on trt is terrible, still a work in progess. Some have had success with adding hcg, cabaser, addressing sleep issues (sleep apnea is a big one), daily low dose Cialis, some need a little help from an anti-depressant, nutrient deficiencies etc libido is very complex.
I tried hcg and could not tolerate it i'm currently working with my doc to find my ideal arimidex and testosterone ratio I feel i'm a fast metabolizer 100mg had my levels at 200. I'm on 160mg just bumped about 6 weeks ago from 100mg and other then energy, strength and recovery going up, libido has gone from non existant to barely existant. I'm currently doing a test run of Cymbalta an snri for depression/anxiety. Serotonin signaling issues can lower libido, which is iron as ssri's etc are known to cause sexual side effects but some may very well benefit.
I'd suggest checking out the board excelmale where it's catered to trt. Just remember that neurotransmitters play a huge role the first time you took testosterone and got that fantastic libido was its effect on dopamine which will diminish with time. Also look into Dr mariano's work, he was able to list off about 20+ possible reasons for lack of libido.
I'd start from the ground up:
sleep-any untreated disorders etc?
nutrition: liver and other organ meats really shine here
nutrient deficiencies: ferritin (stored iron) is necessary for dopamine production and thyroid signaling as well as energy at the cellular level
test/estrogen ratio
dhea levels
thyroid levels
dht
prolactin
pregnenolone
cortisol
adrenal fatigue
gut health
And the list goes on..