I can't feel/ know when should i take poop. my stomach cannot feel it. ?

Fiber: If you are not having regular soft bowel movements, but don't feel the need to defecate, it can be that your rectum is not feeling the stretch that is needed to trigger that "need to poop" feeling. Increasing your fiber intake with a product like Metamucil (large spoonful once or twice a day with 8 oz water) can be helpful to increase bulk. Exercise is tremendously helpful and might try Miralax (polyethylene glycol)

Train your self: I use a simple mantra, "you only need to poo on the days you consume food". If you will train yourself to empty on your schedule, with your morning routine or some other regular point, and do it every day, your body will become paced and bring you better signals.