Been there, done that, too. Maybe step away from it for a while and go back.
I just ripped out sixteen seams (8 wide strips with a strip sewn on each side) that I had stitched together for a mystery quilt (that I bought specific fabric for) and found out (thankfully before cutting it down) that my 1/4" seams were not as exact as I needed and this pattern requires a very exact 1/4" seam to get a 3 1/2" width for the sections. So I have now reset my 1/4" and started resewing them together.