balancing an above ground pool

[Pullingmyhairout]

I've got an Intex vinyl above ground pool. I had leveled it out pretty good using sand and while we were gone for a week the pool bowed out on the sides looking like a football. I drained it and filled again and it bowed again, this time worse than the first. If there's a slant in the yard it's going just one way and the pool reflects that, but the flow is also pushing it out on the opposite side ...kind of like this ( ).. at the top and bottom the pool is full to the rim with a 1 1/2 feet of depth, for a 3 1/2 foot deep pool. Now the left and right sides of that diagram shows the walls protruding out beyond the rims so if you'r elooking at it from the air it would look like two big lips. What can I do?