How to grow userbase?

So I launched a new start-up about 2 months ago, and I had quick steady growth at the beginning accumulating about 200 users right away. But now I'm lucky if I can get 1 new user a day. Now the people that use it, love it. And I do think the site has potential to really take off. It's an article posting and sharing website. I've been successful with Twitter and Reddit in getting lots of traffic to the site. But none of those people seem to be signing up and taking real interest in it. Would like to know if any of you could kindly give me advice on this. Thanks.

The site if you want to check it out is: http://www.newsdag.com/