The twin joke

So me and my hubby keep joking about us going to the doctor and finding out we're having twins. I'm 8 weeks and feel tired and out of breathe. My muffin top has jumped all the way out. I wasn't that small to start so I've been exercising and eating better. I've actually lost a few pounds but my tummy looks so big. My 1st prenatal appointment is Monday and I'm so scared. This isn't our first so I'm not sure why I'm so on edge.