Way to go. Yes, keep writing. Medium is good, but you may have better results using WordPress on your own server. It's pretty expensive to get a hosted WordPress solution these days.

The real answer is WRITE. Don't worry about "book" or "post." I like tagging everything well, so I can sort through my own content later with tags like "leadership" or "analytics." That way I can pull all of my writing around one topic together by viewing all articles with a certain tag.

The word is, KEEP GOING. Congrats on your miilestone. +1 Follower.