Couple of thoughts relative to measuring your pool.

When I measured mine I used my pole with a cable tie snug enough to move to pinpoint the water level at each measurement. Then measured from the water level to the bead for total heighth. When plotting the coves/angles, have somebody help you to make sure the pole is straight up at the bottom of the slope(s), then measure from that point to the side(s).

I also have walk in steps and what you do is remove the strips on each side and bottom. When you replace the liner, reattach those strips then cut the liner at the inside of them with a razor knife.

Hope this helps, Tony