What yarn does the pattern call for? If it calls for the same size you're using, then trust the pattern
Also, is the top of the sock ribbed? If so, then it will pull in a lot
and look much smaller than it actually is.
And, dpns can skew your perception of the circumfrence of the sock. Try sticking your hand in and pulling the dpns up close to your elbow. If what you've knit fits, then you're likely doing okay!