@Conundrum Following. From my observations, low libido and erectile dysfunction are often caused by low free testosterone.
I have an online friend, he has been dealing with low libido and ED for ages. He has good Total Testosterone levels (in the 600 ng/dL range), yet his free T is in the lower half.
The only measure that made his libido return was taking HCG injections.
Seems like free Testosterone has to be in the upper half of the normal range, for libido to work as it should.
I also managed to increase my Total T (up to 590 ng/dL), yet my free T remains low (10 pg/mL).