Sometimes the patterns listed as easy are not quite so easy... as the pattern may have a mistake or missing a step or other vital peice of info. I bought a book and then I went to the internet only to find 45 pages of corrections. Some were huge mistakes ..
So it may not be you.. Did the pattern have you add the seam allowance ? sometimes I have seen templates on patterns and they do not have a seam allowance.
CAn you post a link to the pattern?