Not any help to you but as a 13 year old I was desperate to have a black jumper, which my mother refused to buy me. More ways of skinning a cat! So allowed a couple of weeks to go by and then asked if I could knit myself a jumper and choose my pattern myself. My mother was quite pleased by this and I was duly dispatched to get wool pattern and needles. I arrived home with a pattern for the jumper and it was made on no 11 and 13 needles threeply and black wool!!
My mother was not best pleased but didnt go back on her word and as I was so desperate to have this black jumper, I did some knitting every day until it was made. Never chose 3 ply again or such small needles but enjoyed wearing the sweater for a very long time. My only suggestion is one thing that I did that helped a little. I got a old white pillowcase to put on my knee so that the black showed up in a better way, Have to say I have never made another one in black 3 ply for anything. Another suggestion is to make two different things at the same time , so you do some of your black cardigan in the daylight if possible and while you are not tired and then have a change to something in a lighter colour. Good luck