Well, to my understanding you don't have to burn everything you take in, that would be exhausting lol
My understanding is, it takes a certain amount of calories for your body to just...function. So, by your current weight, just to keep yourself alive you would have to consume X amount (this is the same for everyone, the actual number just varies based on weight).
So let's just *assume* to even function (pump your blood, work your lungs etc) your body uses 3500 calories a day. That is your baseline. Like, if you didn't leave your bed, you could eat 3500 a day just to live and not gain/lose weight because your body is using a lot of that to just be alive. If you wanted to lose weight, you would reduce 500 calories a day OR exercise 500 calories worth a day, for a lost of 1lb a week (1lb=3500 calories).
Your baseline is high because your weight is higher. At say, 300 lbs, it may only take 2700 calories for your body to function, at 250 it may take 2500 etc... so you keep having to adjust for that. (these are just approximations)
So rest easy, you don't have to 'burn' 3000 calories a day!! Your body does a lot of that just livin'
You are just wanting to create a deficit, to consume LESS than what it takes for your body to function and not gain or lose weight .... which is where the combination of exercise/food comes in.
So, if the calculator you used says 3000 calories a day (this is assuming you aren't just in a bed all day, it assumes you are doing daily functions and even exercising -- whatever activity level punched in when you got the number) -- it is probably fairly accurate.
HOWEVER, I would not recommend eating food if you do not feel hungry. If you feel satiated eating 2000 calories most days and your energy level is good, no headaches, you feel good and not hungry -- go for it. You will likely lose faster as well. I see you have a loss already (congrats!), so keep doin' what works.
I hope that helps a little bit, I am certainly no expert but I have been at this a while LOL....
Good luck and much success to you!!