Sweetie don't get too worked-up about, but I always say, "Its good to trust your feelings". To be sure if you're having twins, i got a few signs i've had myself: if it's your first pregnancy, it will be pretty hard to tell because with tiwns, you're more likely to get really bad morning sickness...secondly you show alot faster...and gain more weight (lets double it, if you know what i mean)...and the next sign is if you're already feeling fetal movements, you might feel more movements than normal.
I really hope this helps you out a bit, I had tiwns and these were my very first signs (when i nothiced it wasn't just one baby), and I also had that feeling :), to really make sure, go to your doctor/GYN and you'll know for sure.
at 4:30 PM on Jul. 1, 2010