blonde to ginger/auburn

Hi everyone. I have naturally light/medium brown hair and I currently have bleached blonde highlights and I'm trying to go a ginger/auburn shade at home. I'm not sure how to go about doing this. I have my natural regrowth at my roots, probably like 2 inches of it, and the rest is very blonde from my highlights. I want to use a box dye and I'm worried that the color will process well at my roots but then not stick to my ends because they are bleached and I'll end up with two shades of ginger. I've read that a protein filler would be a good idea before dying it but I'm clueless otherwise. If anyone has any advice on how I should go about this, what steps I should take, products to buy, anything, I would really appreciate it!!