Usually 72x90 is a twin size. Queen mattress is 60x80. If you made a 72x90 it would not fit a queen mattress properly - there would be very little overhang!
I don't measure before/after, but often my quilts come out slightly different than the pattern size. I've never made one that HAD to be a particular size, so if it's bigger/smaller that has been fine with me. I do get some shrinkage, but not sure how much since I don't measure before/after.