Oh GOD. please can someone help me?

Watermelon is a fine snack because it is primarily what its called... water. 1 cup has about 50 calories... so you didn't do much harm. You might feel bloated for consuming so much water, but its good for you, so you're fine, you'll probably feel much less bloated in a couple hours when you're ready for bed. You're not going to lose thirty pounds in a month though, so don't try because you will actually end up losing less weight most likely. Consume at least 1200 calories a day more like 1500 if you're doing vigorous exercise that day. Eat lots of lean protein, fruits, veggies, and whole grains. Limit the amount of fat you consume and make sure what you do get is heart healthy. If you don't get enough calories your body will go into starvation mode and convert all the energy it can into fat stores... making you look flabby even if you are losing weight. Do it the right way and it may take a bit longer, but you'll look much hotter in the end.