You have chosen a way to minimize 'the problem' with the fabric and it looks very nice. I had the same problem with a paneled print one time. I tried tentering it (hand stretching on the bias) and that didn't work. I washed it and tried to press it square and that also didn't work. My solution was to cut off the frames of the flowers carefully and then square up the inner pictures.
This took off enough to look nice. No one missed the outer edges of the deigns. I resewed the frames on. Because I had cut some off of the designs I could used 1/4 inch seams to put them back on. It turned out very nicely.