Welcome to the Quilting Board!
I think this is the kind of math that a teacher once told all of us that we would use someday, but we just don't know when.
There are some great books with different sizes for the same blocks - Around the Block by Judy Hopkins comes to mind. Also, the "All in One Block Tool" is my Bible. There are also some apps for iPhone and iPad.
EQ is definately the answer. If you want to design your own quilts ask for it for your "toy gift" for xmas. I've owned several versions of EQ and it keeps getting better and better. Dianne said she would resize them for you, but if something happens and she gets too busy, I would also be happy to resize them for you. Happy stitching.
Rock Island, IL
This might not be what you want, but could help. If you know the largest block that you want to make, you could go ahead and make that block. Then you could add simple fabric strips to the smaller blocks to make the smaller blocks the same size as the larger one using the strips around them. You could use a contrast fabric to make the smaller blocks stand out or you could use a background fabric that matches the larger blocks and the smaller blocks will just show up in different places around the quilt. I don't know if this makes sense, but in the end, all the blocks will be the same size for putting them together.
Let peace begin with me and you.