I don't care how much you've puked, how big your belly has gotten, or how hungry you are. If you look inside your belly, and there is only one baby in there, a second one isn't going to magically appear at your next ultrasound because you have some nagging feeling that you have twins.
You WANT twins, that does not mean you have some sort of magical insight into your womb that the doctors and ultrasound technicians don't have.
Oh I know, you heard of some random strangers cousin who didn't know about the second twin until birth even though they had lots of ultrasounds. And the heartbeats were in sync so they could only pick up one on the heart rate doppler. Well some random stranger told me that her cousin was abducted by aliens too, and maybe that cousin even believes that, doesn't make it true, and it doesn't make it likely that ET is hanging out in YOUR storage shed.
You have one baby, just like all of the other normal pregnant women out there. You're just being stupid and annoying, and it's obvious that your life revolves around how much attention you can garner which is why you want twins instead of the one that you actually have. I come from a community that would kill or be killed to have what you've got, so stop being so disappointed with the miracle that you DO have.
Be grateful that you can anticipate normal childbirth that will result in a healthy, breathing child, instead of constantly fearing premature labor, long stays in the NICU, and a higher risk of going home with no babies.
A true twin mom who's terrified