I bet I know what is going on with your crochet. To prevent your pieces from decreasing by one or two, you need to chain one, two, or three (depending on the stitch you're doing) before you start your next row. You also need to make sure to crochet the very last stitch on your row. It might look like it is coming off of the side of your piece, but you do need to work it in order to not lose stitches.