I would just add the sashes to the squares if you need to make the sqaures all the same size. I know you can do it! When I'm facing a lack in confidence I simply call upon my quilting Angel and ask her to guide my hand when cutting material or ask her to help me understand a poorly written set of instructions. I also ask her to calm my mind so my full attention is on what I'm doing and not other issues that don't really need my attention when I'm sewing.

I hope this works for you!

hope you ironed lightweight interfacing on before you cut ! makes it so much easier to cut. you might waste some interfacing, but it is easier than trying to do it after cutting on those goosey shirt fabrics.
good luck ! they look so great when done. and they are cherished by their owner.

my dd has made several of these quilts she was very creative and used not only the main print but also small ones that were on sleeves or front of the shirt

You are going to have so much fun with that quilt. Just jump in there and go for it. It will be done before you know it

Here is what I do when I can't get a whole square from the tshirt front: I cut it 2-4 inches small, then I make mini-squares and/or strips from other colors and piece it out to the correct size. There is plenty of fabric in the sleeves and scraps of all the shirts to get strips and squares for piecing out your large squares. And this gives it a bit of a fun scrappiness, too.

You Can do It, Sending Hugs!! your way, You can do it

what is a slipknot quilt?