I just ate like 6000 calories today.

So, today's school food totaled about 900 calories.
Food at home totaled about 600.

And then i went to a hot pot buffet and ate like 6 plates of sliced beef. There were in orders of about 30 slices per plate! That's about 2 1/2 pounds of meat :[.

Even after all that, i stilll wasn't full. Is there a way to get full without eating too much. Also, will it all get stored in my body?

I'm 15 btw.

Well Benny, I'm no expert but I can tell you my opinion. As a growing 15-year-old, your body needs a lot of calories.  You can probably  have around 2,800 calories a day with no fear of weight gain.  You didn't say in your post if you are trying to lose fat, so I'm not sure if that is a concern of yours, but I wouldn't go lower than 2,500 calories.  You would be better to try to add more exercise, even lifting dumbbells for 15 minutes a day would help. 

With food choices, go for healthy, filling foods.  A cup of sliced cantaloupe is only sixty calories.  Add a filling whole grain like cereal or oatmeal and I think you will feel full.  If you are eating a lot of stuff like cheesesteaks and pizza the calories will add up quickly and you may find it easy to overeat.  You may be overestimating your calorie intake though-- I find it pretty hard to believe that you managed to eat 180 slices of beef in one sitting with room to spare.  Was there nothing else worth eating on the buffet?

Make sure you eat slowly and chew very well.  Have a glass of water before the meal, or a bowl of soup so that your stomach will not have as much room for other foods.  You might want to go to the library and see if they have any books on good nutrition and health for teens.