kind of complicated question(s)

okay, so, for the past year, I've had platinum blonde and pink hair. Pink around my face, blonde in the back.

about two months ago, I got bored and dyed the blonde fire-truck red.

about a week ago, I got sick of the red, and bleached it out. Most of the red came out, but it's still pink-peachy color.

I bleached it again, and did a color remover (what I should have done first).

I would love to be platinum blonde again, but I know this just isn't going to happen. So I'm going to save my money, and go get it done in about two months.

now here's where I'm confused at what to do. the color in the back is really uneven. the hair towards my scalp is white, while everything else is that peach/pink color. I want to dye my hair so it's at least even while I save the money to go back blonde.

I bought some dye and developer from Sallys. I bought Feria 6.64 All Out Red-Copper-Red, but the developer I bought is for shade levels 9-10.
 
so:
1. How bad would it be to use the developer I bought today?
2. I have some other developer from a previous dying adventure it's a 20 vol. could I use that instead of the 30vol I bought today?
3. man, I don't even know. had I known it was going to be this complicated, I would have never done the red. lol.

any help? anyone?