UPDATE PICTURE: with questions. I've dug down to level.You will never, ever keep the pool from settling on that pool site. A gallon of water weighs 8 lbs. Multiply that by how many gallons are in your pool and you can bet that you're going to sink!
You must dig down. Building up with dirt is never acceptable. If you want to build up, you need to use crush/er, crush, crush n run, 2A modified w/ limestone. It is brought in in 3-6" lifts meaning you only bring 3"-6" at a time and compact it with a plate compactor and not a hand tamper.