If one set of your QST's is bigger than the other set, it sounds like you have made an error in marking, cutting or sewing. QST's aren't easy, and it will take some practice to make them right. Don't feel bad about that - just practice with some scrap fabric. With the 5.25" squares, the QST's should measure 4" finished (4.5" unfinished) and will match up with your 4.5" unfinished squares.