Your SEO has not gotten off the ground, in spite of all the attention you have paid to the details. You have even paid for an external SEO campaign to draw attention to your site, but it has had a miniscule impact on your ranking for keywords. You are at wit's end. Article writing is the last thing you have thought of to complete your SEO and you are right, but it should have been first.
Articles are content and without content SEO makes no sense. Your keywords are the keywords of content, nothing else. Without content you have no keywords, because you have nothing for them to be keywords of. So step back and take a look at the big picture a moment.
Articles must be provided to your site daily. I said articles, in the plural. One a day will have little impact on your ranking. It won't hurt it, but the help will be trite. Pump in two to three articles of solid content daily. They must be unique every time or you might as well not do it at all. Only then will Google sit up and take notice of you. Everything else in SEO only contributes to what article writing has already done for your ranking. All else is just icing on the cake.
Really, article writing does not complete your SEO. It begins your SEO. So flip-flop your thinking. Begin your site by hiring an article writer and then perform all other SEO tricks. After all, without articles what are you SEO-ing? Nothing.
Everyone thinks SEO is king, but they have forgotten that SEO is merely a servant to the true king, which is content. Google chiefly measures words on sites. The analysis is of words. Keep it in mind and you cannot go wrong.