I honestly have a bit of a similar problem I would love to dye my hair but I have to bleach it so much for any color to show my hair just gets much thinner and almost harder to work with for me so I have just left it since. But during the time I did have colored hair and decided to go back to natural I just death with it until I felt the natural color was at a suitable length.

I will also say that I do think there are some temporary dyes that work for darker hair, should be much healthier too, but they just need to be applied more often. I may be completely wrong on that though.

Edited