Your writing looks pretty good to me (though, as we all know--or should!--one never finishes learning about writing well.) The single thing that has helped me the most is commenting on news-sites--consistently! If you are a recognizable 'voice' in the community of a particular site you are much more likely to draw some traffic when you post a link there.
In general, it sounds as if you are doing things 'right'--probably more so than I do; my tendency is to write the articles, give them a publicity push upon publication (and again on appropriate occasions), and hope for the best. I used to run the title tuner, but have pretty much given up on that since HubPages took away our control over tags. (I'd given up changing titles, pretty much, since getting to the point where the Tuner was advising me to change them back to what they had been previously. Instead, I would add or modify tags based on Tuner input.)
Anyway--I have no better advice than to persevere. You will probably find that your traffic continues to pick up (though with 'ups and downs.) That's been my experience, at least, though I must admit that I'm not yet--after 3 years--where I want to be with views and income.
One last comment--it seems that the last several months have been challenging for a lot of Hubbers, including me. Views for a lot of us have been down, and income even more so. So you've perhaps been fighting a larger headwind to some extent.