[NanetteK]

@jonie I had an extensive chat with Amazon about this yesterday. They confirmed not syncing annotations from other than Amazon-purchased books (unfortunately).

However, I don't know if you found it, but you can send/download your annotations in an *.html-file.

In the Kindle-app (which I use on Android devices and on my PC), in the book, click on the little 'file'-button in the options on top to get acces to your 'notes'. Than there is a 'share'-icon and you can export & send it to Gmail, Dropbox, Evernote, etc.
(On PC-app it has an upload-button.)
(Sidenote: it uses 'locations' instead of 'pages' but at least you can get the content in one go.)