Help the sonograms dont match?

i went and got a sonogram monday and they told me i was 9 weeks exactly well my two friends are pregnant and i loooked and there sonograms and mine looks 100% different there baby is in the bottom of the sac mine is in the top right corner and looks like u can see its arms and feet there just looks like a blob they are both due in december im due in at the end of feb. the doc mesured it 3-4 times could it be older? or what is happening? The sonograms i both looked at of thiers was from 8 weeks- 9weeks