SEO can be a vast work and you can be trying out so many things and be getting it wrong all the same, this is why it is important to employ growing and strategic efforts for the best result. In this age Google is changing towards the use of algorithms that would read in between lines of the content, instead of just deducing the amount of keywords so as to avoid keyword spamming on irrelevant content. Google searchers want to be educated, not just to be shoved with a product on their face; therefore a holistic approach to SEO is your best bet at ensuring you are on page one and you stay there for relevant keywords is typically how seoz approaches this.
One of the things that might be influencing your SEO negatively is the age of your domain, if you are within the one to two years bracket, you might just be trying everything and still feel like you are pelting mud to break a huge stone wall. This is this way, because there are other domains before you that are competing for those same keywords before you came on board. But the truth is that your efforts are building up. To make a more effective effort, you can focus on creating some niche keywords that are searched by consumers in your industry. Once you do you would see your ranks come up, while you are still working on the other direction.
The second factor might also be the mobile compatibility of your search; Google records that 46% of searches are made from mobile. What you might be missing in your SEO is the whole responsiveness of your site. Ensure you check this out and use the Google tool to check your loading speed. If you have never checked this, it is important you do so. Other salient factors are unlinking pages, outbound links and even security.