It looks like you're having trouble figuring out where the end of the row is, which results in you turning too early to start the next row. It might help to mark the first stitch of each row right after you crochet it (insert a stitch marker/paperclip/piece of yarn/etc into the "v" on top of the stitch), so it's easier to identify.

Oh man it's the blue/gold dress all over again

I know there's a problem at the end there, but this is otherwise immaculate. Your tension skills are excellent.

How many chains did you do on the ends to turn? This tutorial is saying to do 4. It looks to me like you either did less than that or your chains were a bit tight, which maybe made you lose track of them at the ends?