This also happens if the body is experiencing great stress and overwork. I myself came across this in the autumn-pre-graduation-session period, when the digestive system throws back interesting knees: that is, you don't feel like it almost all day, and then you can't eat enough; then you want to eat terribly, but the first piece causes a wild heaviness - and then again you feel hungry but it is difficult and unpleasant to eat because of the sensations in the stomach; then you just eat "because you have to", but at the same time you don't quite understand when you have enough and eat "by inertia", or out of boredom, or eating stress, but this only leads to unpleasant sensations that you also want to eat tasty (vicious circle ..)
My advice to you: eliminate, first of all, the causes of your stress. Find a way to relax and not dwell on unimportant things. Remember that on the scale of the universe, everything is transient and not important. Everything passes and this will pass. Little by little, as you regain your calmness, you will feel the digestive system is bouncing back.
If your problem is not stress-related (do you think?), Try not sticking to a specific time frame (14:00, then it's time to have lunch) or somehow limit yourself in terms of food (23:30, which means it's no longer possible). Listen to your body and do not try to cram food into it, "because you have to." The body is a wise thing and sooner or later it will adjust its work if it is not interfered with. The main thing is to listen to his signals. Try to eat only when it is really at the request of the body, and only in a comfortable amount (no more and no less). I believe that one way or another, balance and your relationship with the body will be restored safely. In any case, your feelings of hunger or satiety are subjective things and may not be that important. The priority is the functionality of the body and mind, everything else is secondary.
If the simple actions described above do not help you, then you will have to resort to medical help and make an appointment with a specialist.
This is not normal. The hormones ghrelin and leptin are responsible for the state of hunger and satiety. When a person is hungry, the hormone ghrelin is released, signaling to the brain that it needs energy. After a meal, the stomach is full and leptin is released, which serves as an indicator that "there is already enough!"
You probably have a hormonal imbalance, and you should consult an endocrinologist or gastroenterologist.
I think you will be prescribed therapy: medications and a balanced diet. But it's better to ask a doctor. There can be many reasons, in fact, and the one that I described is not limited to.