It's really simple. You said 3 cars were stopped for you. There are 3 lanes of traffic. The only question is, was the first car in the first lane of traffic, OR in the turn lane to turn down the street you were coming from? If the first car was in the first lane of traffic, then all three lanes had stopped, and the motorcycle was filtering. His fault. But if the first car was in the turn lane, then it's possible that the motorcycle was in the far lane. Your fault.
So, are you sure there were 3 cars stopped for you? What lane was the first car in?