A Question Regarding Conversion In Amazon Affiliate

Hi,
I have an e-commerce site and my site mostly rank higher for long tale keywords which are name of the products. I receive 50-60 visitors every day from google from such keywords. I have around 1000 products pages and content is all unique. In past 14 days I received 750 visitors on my site out of which only 16%, that is near about 125 people went to amazon through my website. I generated only 4 sales out of these 125 visitors to amazon. So there is not much return I am getting as it costs money to get unique content from writers. Do you think this is normal conversion rate? How much you guys are making from amazon affiliate if your site has 1000 unique pages? Also will it be better to target keywords like "which product is best for muscle gain?" for google instead of the product name? Can conversation and traffic increase that way?
Any of you promoting e-commerce site and getting better conversions?

Any help regarding this would be appreciated.

 

This seems correct to me based off your traffic.

 

but traffic is less from google organic considering 1000 unique pages with all original content