hard to rank shopify

So I was ranking number 1 for my keywords. I changed my site over to shopify and bang I lost rankings to page 3. Its been over 2 months and I am still struggling to move from page 3. Any ideas? The new site is built on shopify.

Try making an of-page SEO audit, check the h1, h2, h3, title tags, meta's.. have they remained consistent with the old version of your site? how about the links you have build before? have you maintained the same canonical links?