It really depends on where you buy them. I bought clothes for Peanut and followed the sizing chart and they are very snug on her. $60 down the drain...unless I get another bay smaller than Peanut.
I ordered recently from gofetch and was amazed at the time she put into getting my order right. She had me measure Peanut and by the time I was done she described Peanut's build to me almost as though she was here holding her.