I didn't measure large until 31 weeks or so. I had nomral m/s, and didn't feel movement until 17 weeks, AND this was my third pregnancy.
I did have bad pubic pain from about 20 weeks on. I also had a short bout with preterm labor at 25 weeks. Nothing came of it though.
Finally, at 34 weeks I got an u/s. I was measuring 42cm, yet my mw's and an ob didn't think it was twins
: I had to demand an u/s. Sure enough, 2 babies. They were born 5 days later.
Personally, I really wish I had known earlier. We didn't have a car big enough for everyone. I didn't even have one carseat yet, let alone two. I was getting really depressed and losing faith in my body. I didn't understand why I was having so many pubic bone issues. Afterwards, I felt really good knowing that my body was growing 2 babies!
At least you are suspecting twins. You can at least mentally prepare for the possibility, which is a very good thing. I had NO idea. It was such a huge shock, and I was freaked out with the idea of 1 baby! My second child was only 12 months when we concieved.
GL! Twins really are a blessing.