So currently I use Matrix Lightmaster and Salon Services 30vol and I'm finding it's taking me from a level 3 to a bright yellow, paleish yellow and occasionally a few orangey bits.
I've always been recommended matrix but I wonder if the peroxide is holding it back?
A few years back I could bleach to the palest blonde then tone to white but these days I'm lucky if I can get a pale yellow in places without having to bleach bath after a straight bleach!
Hair can change over the years, so it's possible it's become more resistant.
Don't up the volume of the peroxide, it won't help, it just makes it work faster and that's not a good thing when dying hair ourselves. And I've never found a more expensive peroxide is any better.
Are you keeping it nice and warm while you're bleaching and it's developing?