Going back to gray!

Here's my dilemma.
I went gray early (started at 13), I've been coloring it for 25 years, but I have to do it every 2 weeks. My "natural" color was a very dark brown, I color it to a more medium brown, but my regrowth is perfectly white.

So I decided to let it grow in, do more highlighting etc...

Now my regrowth is about 1.5 inches, but my hair is past shoulder length.

I figure I am going to have to cut my hair at some point, but I HATE
short hair on me.

Any ideas for keeping my hair somewhat long...say past jaw level, and yet working in the gray faster?

I plan, by the way to weave in blonde highlights to my new white hair.

But my hair has undergone so much treatment to put down the brown on the gray, then some of its been highlighted...

I just can't bear the thought of 2 - 3" hair length.
I'd be inclined to color it back to brown.

But I am tired of doing it, spending the money, the time, and I wonder about the chemicals over so many years, 26 times a year...

Any ideas?

Thanks...
I know you gals are not my age...but maybe you've seen something done to someone else that worked?

Kathryn