pulsating/flutters in belly

[monicam112233]

I have been having this problem from few months now. I even thought Im pregnant because pulsating was so unusual and strong I thought its a baby (never been pregnant before). but my last time sexually active was about 8,5months ago and I've taken multiple home pregnancy tests (all negative), then took a blood pregnancy test at a clinic which indicated im not pregnant. I've had all my periods on time too. then finally went for an abdominal ultrasound, the doctor said there's nothing wrong there, also, no baby seen, so I guess I can rule out pregnancy and also rule out abdominal aortic auneurysm, because on description of my US results was written theres nothing wrong with my abdominal aorta. it keeps me up at night. ive been dieting on and off for about 7months now, loosing weight then gaining a little then loosing again. im obese. i am about 245lbs. im 24years old. 5'5'' height. i smoke cigarettes. it keeps me up at night. it feels as if something is moving around in my belly and pulsating constantly in different spots on my belly. im so fed up of this. any advices will be appreciated. it seems to lessen a bit when i dont eat anything but only for short time.