Hi Carolyn,
Since the liner is only a year old I guess it's possible a seam opened. Chasing my leak last year, a pool contractor told me that if a seam is going to open it will do it usually in the first couple years. Someone else may kick in other thoughts on this. I next started with the dye around the junction of the floor and sides at the deep end. Had already figured it was a deep end leak because the leak rate didn't change as the level dropped. Have to go very slow with the dye. Position the hose, squirt a little, and wait a little. I was losing about 3 quarts a minute and when I hit the spot it was obvious. Found it within an hour. 3 small slits inside a 2" diameter circle maybe caused by agressive use of the pool vacuum brush. You also need the water to be really still, no currents to disperse the dye. To see how difficult finding a leak of this size I stuck a garden hose on the bottom and started a siphon and set the rate to be my 3 quarts per minute. Then was able to see what to look for with the dye. Funny thing, with the naked eye I never saw the slits, until I knew where to look.
Hope this helps a little more.
Al