I am 8 weeks and 4 days pregnant, my fiancée mom thinks I am bigger than what women should be at 8 weeks, twins runs on both sides of his family and not on mine, his mom thinks its twins I have pain under the left rib cage and when I lay down my back will hurt for a few minutes, both sides of my abdomen are hard at times to

What did the Sonogram show? You have been to an OB-GYN , haven't you? Anything else is like reading tea leaves or consulting Tarot cards.

No I am waiting tell after christmas to go, I took a pregnancy test was positive and around week 4 I got sore boobs and now its 8 weeks I have sore breast nipples

Congratulations... but seriously... no way of even guessing on if its twins or not until then. But they can tell you for certain.

Okay thank you so much, at 8 weeks almost 9 on Tuesday is the baby up and moving around

Its barely more than 1/2" long at this point... the link shows a chart based on age of the fetus.

Average fetal length and weight chart | BabyCenter (http://www.babycenter.com/average-fetal-length-weight-chart)

Fetal development week by week | Pregnancy images | BabyCenter (http://www.babycenter.com/fetal-development-week-by-week)

Moving yes but about the size of a large bean, not a large baby

At 8 weeks it would be impossible for you to feel fetal movement.