I've been dyeing my roots for years with igora royal 12.2 and 9% cream peroxide, just to make my natural blonde hair a bit lighter and more ashamed. However the last six months or so my roots are coming out really yellow, so I have to do them again, tried new colour and peroxide but have just realised it started after going on HRT. What can I do to solve this, I'm so sick of having to repeat the process or hide the yellow with dry shampoo! Shall I try 12% or switch to 12.1? Help!