Cutting like a fool

I've been a slicin' maniac the past week.  I thank the quilting gods for inventing rotary cutters.  I cannot BELIEVE that up until 1980-something people made quilts with scissors.  I remember getting blisters from cutting through so much fabric...
Anyway, I've been doing a little bit each day.  First I finished all the prints, then last night the solids (much fewer pieces).  This noon I got about 1/2 of the white cut.  The white is Kona "Snow" and I love it.  It's not pure cold white, but it's just so slightly warm that it doesn't look wrong with cool-toned prints.

I've been calculating the percentages of each type of fabric to make it about equal to the model quilt.  But I ended up with WAY more center squares than I needed, just because it was easiest to slice up a whole row.  I don't want to reduce the percentage of white very much, because I think it's going to be really necessary to tone down all the bright prints.  So most likely I'll make some other sort of block out of them to use on the back.

Of course I couldn't resist stitching up a couple blocks to see how they will look,  and they are BRIGHT.  But that was the idea.  They are still coming out slightly small, like the friendship block did.  It's so hard to figure what I'm doing wrong.  Maybe the ruler is slipping as I cut, or maybe my seams are more than 1/4, though I test and test and test....   So I decided to just forge on and see what happens.  The worst case is that I will cut them all down  to 10" even.
I haven't taken time to snap anymore photos, but I will this weekend for sure.