I made the cake for my son's birthday and the buttercream ended up too airy (for lack of a better word). It was definitely fluffy and I had air pockets when I frosted the cake.

I started with my basic crusting buttercream recipe and I know that I whipped it for too long while trying to get the right color.

Would adding more sugar to the icing have fixed this? Or would I have to start over? It tasted fine, but was more of a whipped frosting than I wanted.

You can add more powder sugar.