Advice please!

Hiya everyone,

So, up until a few months ago I used to dye my hair blonde, and did this for around 3 years. Ive got a slightly strange natural hair colour ranging from dark brown underneath, to dark blonde on top, so of course I used to use bleach to get the shade I wanted.

Around 3/4 months ago I noticed my hair was really beginning to feel the strain of all this bleaching so I decided to dye it brown and give it a break for a while. This worked wonders for it and it now feels in great condition. However, I miss being blonde and Im starting to think maybe now might be the time to try and go blonde again!

My problem is though, I bought a l'oreal high lift colour with 30 vol developer, and did a strand test (thank god that I did!) from the darkest part of my hair to see how it would turn out as Ive never used it before, and the difference between the 2 inches of untreated hair growth and the 4 inches of bleached & dyed hair was astronomical!
The previously processed hair turned the vanilla champagne colour that it was meant to go, but the new hair turned a light brown colour.
I would be quite happy to have the light brown colour that it gave to the roots with a few highlights through it if this means less damage to my hair in the long run. But what would be the best way for me to go with regards to evening out the previously bleached hair so that it would match with the roots?

Thanks :)