I am not sure about draining the water or not, but if you do start over I would suggest renting a laser level and rod from a local hardware store. They are easy to use and take all of the guesswork out of leveling. I work in construction and use them every single day.
Set the laser up outside of the pool area, elevation doesnt matter here, it will self level as well. Take the rod and the beeping device that attaches to the rod and go to the middle of the pool, place the bottom of the rod on the ground, then place the beeping device on the rod level with the laser (should be a continuous beep). Once its level in the middle of the pool area, walk around the pool area placing the bottom of the rod on the ground. This will give you spot elevations where you are high or low. Adjust spots accordingly.
