Banana skin yellow&white....How can I get it back to more natural & less dayglo?

*stars*

I was wondering, well hoping, for a little advice please? I have been using B-Blonde’s highlighting kit over a dark blonde / light brown base, with great results. However, I (stupidly) used a different product to bring up my roots (L’oreal) which at the time, I hadn’t realised the significance of white Vs blue bleach, and I ended up with *very* yellow hair
I didn’t panic (as I did years ago & give myself a chemical haircut) & after trying Provoke Touch of Silver shampoo to bring it down, I put a semi-perm platinum toner over it for 10 minutes which took the edge off but I was still an unpleasant shade of yellow.
I let it settle & then used the high-lift blue powder & 30% developer from B-blonde which although has lessened the worst of the bright yellow, has left my hair with the well-known banana skin yellow shade for the most of it, with some whiter streaks (around a 10, plus the yellow!).
I want it to be a more natural shade of blonde / blondes so was looking at my options. I am not currently in a  position to go to the salon & in all fairness, where I am, there aren’t many trustworthy colouring stylists unfortunately.
I was considering using a demi-perm as either a base & then use lowlights over the top in a couple or so shades, or to leave the base & just put a demi-perm toner over strands pulled through a highlighting cap to give it some colour & make it less ‘in your face’. It wouldn’t be *as* bad if it was white all over (although I had this several years ago when I was younger….!) but the yellowy tinge just isn’t my style!
My hair fortunately is still in good condition & I have been soaking it in protein masks & conditioners, plus always use argan oil etc after washing – I don’t blow-dry or straighten it either, and it does still look in good condition & feels good to the touch.
I have been looking at the Ion / XP100 / Wella Colour Touch & Koleston ranges.
It is made slightly more difficult in that I have short hair at the back but is much longer on top – if that makes any difference?
There is a local Sally’s store so I’m hoping to get the appropriate shades & developer from there but obviously would really appreciate some help along the way?!
Thanks ever so much for reading this in the first place!
Best wishes,
Sarah