I'm curious to know if my intuition is right or not too... Have had a feeling about this pregnancy being twins and lots of "twin dreams," got bigger wayyy faster (this is my 3rd pregnancy), movement since 9 weeks, really bad M/S, lots of kicking almost all day long, crazy hunger in spurts (never had any of these with the other two), and now at 18 weeks I seriously feel and act like I'm at the end of the 3rd trimester. I get dizzy, crampy, and just feel awful with any exertion, bending over, picking up my kids, etc. It is SO much different than my first two, who were relatively easy pregnancies.
Of course, my midwife says my hCG level at 12 weeks was normal for a singleton (I think that's quite late and not as accurate as an earlier test), uterus is normal size, she only palpated one, and we had trouble getting the HB twice because the baby was jumping around so much. She also says that diastasis (ab muscle separation) could explain how I look 7 months pregnant at only 4, and also the early movement since the muscles are pushed away and you can feel the baby(ies) more easily.
I'll keep you posted on what I hear next Friday at the U/S!
BekahJ -- did you ever get the U/S or find out either way?