Help!?! with blotchy hair

Thanks!

Hello all. I'm new.

I've been lurking this board for a while and I have some ideas on what to
do with my hair, thanks to everyone for the good advice on this board. I
just thought I'd run it by y'all to make sure.

I have hair a few inches past my shoulders. I'm trying to grow it out.
In the past 8 months I've dyed it (permanent) about 4 times. OOPs! I
didn't know any better. NOW I do!
In the months before that I had it done professionally a few times in
demi-perm with some highlights too.

My natural hair color is a dark blonde/light brown with some red AND ash
tones to it. (I know, weird huh?)

Since dying I did a really dark brown back in November and then a lighter
shade of brown the couple of times between. More recently I dyed a med.
brown that brought out some more red. It was starting to get a lot
blonder and lighter, then a month or 2 later I dyed it a really dark brown
again, like last November.
But this time, it looks like where I had highlights before turned out
looking black and then there's other spots where the blonde is showing
through. The roots are lighter and some of the ends are lighter too.
Since reading the advice on this board I've been using Olive Oil and Head
& Shoulders shampoo to try and lighten up the darkest parts.
It has lightened up a little but the color is just too blotchy all over.

Now, I'm thinking that I really just need to use colorfix on my hair (strand
testing first) to get rid of ALL that old dye in my hair. Then use a protein
filler (I want to get some Deep Fuel by Redken) Then after 3-4 hours (at
least) then I'll use a demi perm in the color that I want in a couple of
shades lighter with an ash tone to it.
This will be a whole weekend thing for me!
Is this right for me? Any advice, changes, suggestions on this?

I'm SORRY this post is SO LONG! Thanks for hearing me out.