Our Milkyway Galaxy & Local Group?

As you already know our Milkyway Galaxy is spinning and we are in one of it's small arms the Orion Arm or Local Spur, but since it takes the Earth or should I say the Solar System 200,000,000 Million years roughly to circle the Milkyway once isit possible that their is other galaxies in our local group that we dont know about on the other side? Maybe our local group is far larger than we think or Andromeda isn't the largest galaxy in it, but we can not see any of this due to the galactic core & dust blocking our veiw? Or do we know for a fact that our local group is everything we have seen in it right now.