If you use Eleanor Burns methods, which you cut bigger and cut down to size, you wont have a problem.
If I cut to size mine will not turn out right either.
I belong to a group of quilters and all our blocks have to be a certain size and now I dont have a problem.
Please dont give up, it is a learning curve so be sure and try Burns methods. Her shows are on
http://quilterstv.com and at her website
http://quiltinaday.com
Quilting keeps your brain in tune also.