Please stop the concern trolling, it isn't.
The mere fact that the polling averages haven't consistently been 55 Clinton/37 Trump for the duration is concerning enough for me.
Which is kind of the context for your misery, and why your predictions have been so bloody bleak. Trump's best in the Huffpost average was 43% back in July after the Comey findings. The polling data we have of undecideds showing that they dislike both candidates intensely, but they loathe Trump.
You're going to get shifting around the margins - look at 2008, you had polls in the last 2 weeks that ranged from Obama +3 (Fox News... cough) to Obama +11. Basically what we're getting now.
Well, I still think she's at least 75% likely to win, and my expected outcome still has Clinton with >300 EV. I'm just saying, this was probably the Democrats' only chance at a 1964/1936 style win in a human lifetime and they threw it away by picking Clinton (and not running anyone better than Sanders against her).
Not even close. Pretty much everything is stacked against the Democrats this year, even without such a lame candidate as Hillary. One party trying to win a third term in the White House is very difficult. The populist right has been a very powerful force on the Republican side, and Donald Trump has played them masterfully. He has won the mantle of the "change candidate," and that gives him a huge advantage. Bernie Sanders might have given him a run for that mantle, but the populist left scares Americans, while the populist right is now mainstream white America.
Had Donald Trump kept a lid on inflammatory remarks, and had he had a firmer grasp of policy and been better in the debates, he would be winning this election handily. He could have beaten any other Democrat - Bernie Sanders, Elizabeth Warren, Russ Feingold, he would have wiped the floor with Martin O'Malley, John Hickenlooper, Andrew Cuomo...
This election cycle was a perfect storm for a Donald Trump. He captured the mood of a nation and put it in a bottle. His nomination wasn't a "golden opportunity" for Democrats to paint the map blue. Not even a bit.