Infant clothing

My favorite outfit is a snap button sleep n play with feet. And since my lo is now 3 months she is growing out of a lot of the selection i have at home. So i went to target and got a 6m sleep n play. It looked pretty big. I even "tried it on" her and then threw it in the wash. I went back to target and got another 6m and 1 9m of the same style. I swear the second 6m I bought is bigger than the first. How can this be if its the exact same brand and the exact same size? Its even the same style, button up sleep n play w feet. So is it possible it shrank in the wash?? I put it on cold/cold and low dry. I just can't believe what a drastic difference it is. Also the price is just ridiculous. How many clothes do you own for your little one?