That's OK, once you're finished putting insulation and drywall up, you go buy more insulation and start making acoustic panels.
There is something to be said for stopping when 2/3 of the drywall is up.
True enough, at the 3/4 walls drywalled mark the room actually sounded not too bad. With only 2 walls up the room had a noticable "boing" ring to it. Kinda fun to clap and boing while we worked. All the walls are up and screwed every 8 inches or so to the resilient channel. This stuff is cool. The walls literally float off the studs.
To cut down on the chances of shorting out the channel, thus ruining the sound decoupling, we made up a handy little jig and marked the floor with felt where the studs were. Then we just laid the template between studs and screwed on either side. This was my sunday. Going around the room and earning a drill blister.
This is where things stand after a weekend of work. The walls are channeled and boarded and the ceiling is ready with channel. We put up a sheet of drywall over the door opening just for fun to see just how quiet it got. The furnace, UPS and HRV running 20ft outside the door were completely gone. My wife was yelling from the top of the stairs to help come unload groceries and we couldn't hear her. Awesome.