also, if you try to print the patterns directly from the internet, they are not scaled correctly... so make sure to save the JPG to your computer and open it in a photo program (Photo Editor or something like that) and print it from there.
The 11" pattern I just printed and it just fit on a 8x11 paper, so if you were able to print the 15" on 8x11, I think it's not printing it accurately. (make sure the program you are printing it with isn't set to "scale to fit")