Fabricnut

I'm almost done with the top of this Halloween tabletopper. My sashing doesn't line up right for some reason. I ripped it out and tried to realign it better but it is still "off". I sewed the sashing to the horizontal blocks first then made one long vertical sashing between the rows. I don't know if I stretched the fabric, if I ironed too much, or if I cut off too much when I tried to square up each block, (The first time I really tried the squaring up thing.) Any suggestions will be appreciated.
I saw Bonnie Hunter talk about using scraps up so thought this would be a good time to try it. It sure did take longer than I expected for just a tabletopper. I just have 2 more borders to finish.