Morning sickness

Hoping to hear from anyone who can describe what their pregnancy sickness feels like? I am a little baffled mine seems so different to how it is described. Rather than feeling nauseous, or as if I am going to throw up, mine feels like an uncomfortable pain in my stomach, as if I have eaten too much food and about to pop (that uncomfortable post Christmas lunch feeling). It is constant however only begins once I have had something to eat, it doesnt appear first thing when I wake. It is definately worse at night, after dinner and when trying to sleep. I am 8 weeks pregnant.