The closest I've come to deliberately creating a fractal to match the way I was feeling was when I broke my right hand. Every time I moved my fingers a spike of pain shot up my arm and made it almost impossible for me to use the hand - and I'm right handed! The image I was working on at the time was all pale creams and delicate texturing so I threw a spikey red shape into the mix. Can't say it made me feel any better but I did reflect the pain I was in.

Other times I find that the colours I choose for my images match the way I'm feeling - so I use strong colours when I'm happy, paler colours when I'm unhappy or feeling quiet, and darker tones when I'm angry etc.