I don't think your site has failed.
I think you just have not aggressively created content for it.
It's only been 14 months old.
40 articles is not enough.
Also, 1300 words, on average, is kind of middle of the road.
It doesn't really tell me about the quality of your content.
Quantity, after all, is not quality.
If I were to rehab this website, what I would do is first, make sure that I interlink every single one of my existing articles to each other using calls-to-action.
In other words, when somebody finds themselves on one of your pages, you call them to action to visit other pages.
So you stretch out one visit into many page views.
This can increase your income because the more pages they view, the higher the likelihood that they will click on an ad.
The second thing I would do is to create more content.
Sure, you're targeting long tail keywords, and I'm assuming that these are questions, but find related questions and put them together in the same article and make sure that you truly deliver on the search intent behind those questions.
Don't just mention the keyword every once in a while to stuff your content.
That doesn't work, at least not anymore.
The third thing that I would do is I would build a mailing list.
Please understand that the vast majority of people that find themselves on your site will never come back.
That's just the cold hard reality of blogging.
You have to find a way to get them to come back, and that's where your list comes in.
Of course, this would mean coming up with a freebie offer like a free ebook or a checklist or some sort of gimmick to get them to sign up for your mailing list.
Once you get that, then you have a self-sustaining traffic machine. People on your list are encouraged to share your content on social media.
The fourth thing that I would do is I will also hire a virtual assistant from low-cost places like Fiverr or if you're looking for quota-based assistants, places like Cognoplus to share my stuff and promote it on social media.
Don't give up.
Forty pieces of content is not enough.
Try to shoot for 100 to 150 posts.
Also, make sure that your content is better than your competitors.