I am an athlete who practices 4 times a week and lifts 3 times a week. I checked around and did all these equations and they all said that I should be eating 3800 calories per day in order to maintain my weight (I burn 3800 per day). I counted the calories I consume in a day, and it was only 2000 or around there! Should I eat more? What will eating 2000 calories do to me?

well, every body is different so just because you "should" be burning 3800 calories a day doesn't mean that you actually are. But that is still a pretty big difference between intake and expected output. Are you sure about those 2 numbers? Are you loosing a lot of weight?

Assuming you are staying pretty constant, you might benefit from increasing your caloric intake. Without feeding the body properly you can't get stronger like you should. Try adding the calories in protein and carbs only, and add them in 200 or 300 calorie increments. Stay at the next level for a week or 2 and see how it goes. If you like the results, up the intake again and see how it goes. Then back off when you start adding just fat.

yeah- to expand...
I am male, 198lbs, 6 feet tall, a volleyball player, and I also lift weights 3 times per week. My weight has fluctuated from 220 to 175 in the past 5 years. However, I didn't start weight training until a year ago (shoulder injury also delayed this, so its only been about a half a year total). I want to get as thin in the waist as I was when I was 175, but I know that since I am lifting I will be gaining mass. To try to lose weight, I have been eating just turkey sandwiches and salads and cereal and fruit every day pretty much with some protein shakes, and that is what has amounted to 2000 calories per day. Since I started lifting, I have found myself to be constantly hungry, but I still only feed myself as much as I used to, so I guess I should up the calories....the question is what to eat? When I first heard about the 3800 calories thing, I immediately wanted to go buy some Oreos

Up the calories! How about a steak and baked potato? Or maybe some fried chicken? What about seafood gumbo over a bead of rice? Any of this will give you both protein and carbs - as well as some fat. And with needing to basically double your caloric intake that is OK. Just don't go overboard on the fat, and only add in calories a few hundred per day at a time.

Oh, and a couple of Oreos won't kill you (as long as you aren't a diabetic or something like that). I personally like the fudge covered ones ;-)