It would only dye well if you used a dark colour, as the differing bands would still be there in a light colour. You should be able to use natural dyes from round about, although with a finished article which is large like a jumper it is very difficult to get an even dye finish anyway. Using a mix of colours, rainbow, would be too much for an aran and hide the pattern, wasting all your work.
Just be proud of it
. Anyone can buy a jumper, but not many can spin and knit it themselves
For next time, blend all your fleece together before you start carding. I suspect the fleece you used had varying colour from end to end, or had differing exposure to sunlight which makes white wool go yellow.