Anybody having twins after being told they were just having 1

Heidi • This is my 4th pregnancy. I have had 3 previous misscarriages. I am beyond excited to be a mom and I pray to god everyday that this little peanut sticks!
I'm wondering if it has happened to any of you that the doctor said you were only having one child but later on ended up being pregnant with 2? I'm 17 weeks and I can't shake the feeling that there's more than one in there. Although I seen with my own eyes in my 9 week ultrasound that there was just one, could one been hiding?? Just a weird feeling that I have.