I wish I could say that having centred all the strips to the line the 2 side edges were the same - but no. Even if you scrutinise the picture below I don't think that you'll see the problem with the top strip. Just take my word for it, I had to draw several chalk lines on the front whilst deciding where to sew the side border strips.
I can't post any more photos until I charge my camera.
I did all this at Saturday Stitchers, I sat next to Jacqui and discovered that we go to the same Chiropractor. I am not suffering as much today as after last time as took a big fat pillow to sit on and I used the heat packs last night, and ensured I did the leg stretches. This is how I have to manage it - it won't go away so I just have to learn how to live with it.