Site not showing up in SERPS (Top 100)

Hi all,

So one of my amazon affiliate sites is not showing up in the top 100 of the serps at all.

I first put the site up in mid april and put a couple of basic articles on it and left it for a few months due to other projects. Over the last 2-3 weeks or so I have totally improved the site, it now has 3x 6000 word articles and I have on page optimised.

The site indexed no problem at all, it has no penalties either.

Any ideas what is going on here?

Thanks