Why do I feel sick after drinking what seems to be a lot of water?

I have a moderately healthy eating habits, but I have mental problems that effect me physically. I do get out and go on walks quite a few times a day, but no matter what I black out.. my normal water intake varies, but at minimum is 3 bottle of water that each hold 500ml. I also have a bottle that can hold about 800 ml that I'm trying to add to the bottles of water.. after the 4 which is 1500+800=2,300ml causes me to feel sick even though it's still less than what's recommended at the least..

My height is 5 feet, 6 inches

Weight is 100.7 pounds

16 years of age