Common ?

I had a baby 8 months ago but I still feel pregnant ! At first I lost all my baby weight but now I’ve gained 20lbs I feel nauseous all the time I even feel stuff moving in my tummy ( I know it sounds crazy ) but I’m positive I’m not pregnant I’ve only had sex once since I had my son plus I’m on birth control it’s just weird I told my doctor she acted as if it was normal but I don’t think it is