Pattern change halfway through?

by Whittney
(Idaho, USA)

I genuinely don't know how I did this, so any insight you could offer would be great. Image attached - easier to see than to describe, I think.

You can see on the left hand(hopefully) side of the image - the pattern stops looking like the right side and starts looking like the wrong side, I guess is the best way to describe it? those last two sets of the pattern look like the back of the rest of the blanket.

It's a simple pattern (8k 8p for 12 rows, then 8p 8k for twelve rows). And from my notes I've kept to the pattern, but from the look of it somehow I... stitched the wrong side on the right side??? or something? Or is it a simple case of not switching to the next phase of the pattern correctly? Except I've kept a note for each row and I'd SWEAR I did the pattern changes right.

I'm less looking for how to fix it than how on earth i managed to DO that in the first place.