Silver Needle

I am supposed to be making a Jinny Beyer Quilt for my grandson's graduation which was last year. It said for beginners. Ha Ha. It said use exact 1/4" seams so i cut some scrap fabric and sewed seams until I can mark a place for a sewing line that presses out to equal an exact 1/4" seam --- i'm happily sewing all these strips together and realize in the fine print in the corner the total of these strips should be 17" Now some of these pieces are only 7/8" wide so ripping all (by which I mean a LOT) of the constructed strip sections apart is not an option. I'm almost done by the time this little tidbit catches my eye. My pieces vary in size but are all in the 18" range.. I'm going to see the family in March and I know I will be asked how its coming. I'd like to drown the $300 undone piece in the river but don't see that as an option. I need to recut all these strips some of them in 7/8" wide pieces and then resew them into something that looks like a block. I Would like to use my new Bernina 880 as it has differential feed so that the seams halfway match up. But what do I do to make these blocks turn out halfways square. I'm afraid its going to be a mess no matter what I do. And by the way HE chose the pattern. it looked so simple. SOMEONE SAVE ME - Give me some encouragement; some inspiration; some suggestions.