not a very complicated problem at all... you just didn't do your research.
nandrolone (Deca) commonly raises prolactin, which can wreck the libido. one needs to take a dopamine agonist (pramipexole, caber, etc). also, the half-life of deca is extremely long, and should have been stopped prior to the testosterone.
you also don't mention using an aromatase inhibitor, so you might have high estradiol (estrogen) levels.
easy solution... get bloodwork and see where all those levels are at, and treat accordingly.
next time do your homework...