The simple fact is this: If you are not losing weight, you are not in caloric deficit.
It is as simple as that. Usually, the problems are:
- You are not putting everything you eat into the program
- You are underestimate the energy in what you eat
- You have overestimated how much you actually move around every day
Often a combination of all the above.
There are a couple of ways to come around this. Firstly, in my experience there is no way to have long term weight loss without continous effort to keep yourself in caloric deficit. You will automatically start eating larger portions if you don't monitor what you eat.
If you have a sort of stable eating habbit, where you eat more or less the same every day, you can just try removing something from your usual meal. I for example ate bread to every meal, by removing it I more or less cut back 200 kcal. By removing other such things from my diet I managed to put myself in caloric deficit without weighing a thing.
Mostly though, the easiest way to remove all sort of biases is to simply weight everything you eat. This takes a lot of dedication, but it is a sure way of knowing exactly what is wrong with your diet. It makes it a lot easier to diagnose a meal plan. After a while you get a feel on how much you should eat and you only weight your food if you come to a sticky point.
Whether you burn 1800, 2000, 2600 or any other calories per day is quite irrelevant. Just cut back on your calories until you lose weight and take it from there.