Why can't i shake the feeling

Ok ladies, this is my 3rd baby, (current youngest is 3 years old). I am huge. Had pregnancy symptoms a week and a half beforr i missed my period, wolfimg down any food in sight (literally), kept trying to tell myself it was PMS gone haywire lol. Tested VERY VERY positive 1 day after the day my period was supposed to start, very strong positive before the test was even done loading. Have been able to SEE and FEEL movement for over a month now, am now currently 20 weeks 1 day. My head won't get rid of the idea that I'm having twins and its bugging the hell out of me... anyone else experience any of this before?