that's too low visitors if you want to make revenue from your site, mate. it's better you work on page seo and start targetting any keywords of some of your pages.
I believe 20 visitors from search engines is okay. As you add more quality content your traffic will increase. I didn't get that much when I first started as I didn't understand much about keywords and SEO. You are off to a good start and should get better.
Probably a good start, but you need to aim higher. Have you tried sharing your blog contents to social media? It'll help to generate more traffic.