I think your website lack in some other side. Are you added your website to google webmaster or not. How many backlinks are showing in webmaster
A common mistake of most of the e-commerce sites, is that they are using thin description of the items, or duplicated one from another site. Add fresh content or extend the current pages and play with the keywords (do not stuff em), then share the content on the social networks
Repeat the off page but merge it with on page and social media. SEO its a nice work that you need to update it over and over. Don't just stop because you will never see the results.