As Harry said, the myclippings file holds all the highlights and notes you made in chronological order.
I would have recommended the Kindle Mate application (
http://kmate.me) for easier sorting, export and backup, but unfortunately it only works with Windows (now, if you are using a virtual machine...)
For Mac, there is this, which at least gives you a better overview over your highlights:
https://tom.alby.de/software/kindle-clippings-manager/