It kinda sucks not being able to write a full review without avoiding spoilers, but i shall try to do it without revealing anything, in case anyone wants to watch it!
The premise of the series is indeed interesting and the main message of it, as you said yourself above (
how little things (we think) can cause horrible consequences.-Hannah does mention the butterfly effect at some moment, iirc) can offer some food for thought. It actually brought to my mind J. B. Priestley's "An Inspector calls" (have you read it/watched it, btw?

). However, the whole execution is rather poor- bad, unrealistic writing, with all the possible cliches and a plot that can not justify the existence of 13 episodes (13 reasons? Maybe 2-3 i'd say).
Anyway, yes, thruth is that i shed some tears but not for Hanna. I actually got emotional with other characters, such as Jessica, Alex and even Justin in the last episode.
P.S Teens are indeed the biggest drama queens, i was one myself some years ago, so i know how it feels, but Hanna's character takes the concept of it to a new level

I felt that she was just a self absorbed, but most of all a weak person. And, to borrow a line from one of my favorite movies
"It's a hard world for little things"