I do this thing where I drink a LOT of water, about a liter, in a very short amount of time (say, 10-15 minutes) just to feel fat and bloated, and then when I pee I feel super skinny and thin? It makes me feel as if I lost weight, even though I didn't. I do this multiple times a day, and my father says I'll get sick if I drink so much. Is it normal?

No, it's not normal. It sounds like you're trying to do the water diet, which doesn't really work. If you want to lose weight eat vegetables and fruits.