Right now, you have a problem of lacking players that are playing, maybe you should add a bit of bots into the game so that its never a long waiting period. I have tried to play the game and joined the lobby but I was the only player and had to wait couple minutes and there was still no other player so I quit, I am sure others would do the same, they would join and wait a while but if no one else joins than they would probably leave too and you will never have enough players.

However, if you add some bots and people could play no matter how many real players there are than you can actually have some people coming in all the time from playing and eventually replace the bots. That's at least what I can think of, if you have any better idea to bring in more players you can do that too.