Even Page 1 Custom Map lobbies can take a while to fill. Was waiting 5 minutes to play Night of the Dead. Sometimes I login to NA server when it's early morning coz it's night time there and traffic is much higher. If I recall correctly, SEA population is about 60k players? This would have went down a bit as players move on...until the release of Heart of the Swarm which would bring in returning players and fresh blood.