Get out of beta. You're artificially constraining growth.
For example, I wanted to try it out. Couldn't. 1 user lost. You will struggle your entire startup's life trying to get as many people to use you as possible. It's not like you don't have bugs after you launch. If you're a decent startup, you will be agile and you will change and fix things as they come in.
Since this is a news recommendation engine, no one is going to die or lose a ton of money if your app isn't perfect out of the gate. So make it easy for people to try it out, recommend it to others, and get as much feedback as possible so you can make it better.
If you're worried about growing too fast...well, you should consider that winning the startup lottery. Chances are that's not going to happen and you should be so lucky.
Good luck launching!