twin dream 👶🏻👶🏻

Ursula
I'm 19 wks along, and been tired like crazy (having 4 kids already doesn't help lol) I took a nap the other day and ended up having a dream about having twins. I already had an ultrasound at 9 wks and was told there's just one and the sono is just one heart beat. 
I posted on FB about having a twin dream and how glad I was that I know there's only one in there lol. Well now I'm getting a bunch of ppl just teasing saying "are you sure?" But others stating that it could've been missed and vanishing twin etc etc. so now I'm slightly nervous for my 20 wks ultrasound coming up lol 😳 anyways this has made me curious to know if anyone did find out they were having twins after being told it was singleton at first.