I believe that this ran true to size. My daughters hardly wore the footed pajamas that I mostly received as gifts because they were too hot. They would scream at me if I tried to put them on. Usually if something runs smaller than the size on the tag, I have posted it at the size that it appeared to be and then just noted what the tag was.
I recommend going to the do surveys for credits tab. I think it was the Daily Surveys that give you the credits right away for signing up and then I did 3 surveys and got 900 points. I also tried the Toluna one but never received the points for doing the surveys.