LO weight gain

Jessica • 34 Pregnant w/ #2
My LO weighed 10 lbs 5 oz (95th %) and 21 in.  (92%) when born. At his 2 month check up he weighed 13 lbs 8 oz (74%) and 24 1/2 in (94%).  Dr was surprised his weight dropped such a large percentile.  I am breastfeeding but I am not sure that's the problem.  He lathes fine and I am pretty sure I produce enough. 
Has anyone else's LO dropped percentiles so drasitcally?