2 week growth spurt???

JD2007

My baby turned 2 weeks today and hasn't wanted to leave my breast ALL DAY.  I'm exhausted.  She isn't yet up to her birth weight so we're going to the pedi often for weight checks.  So far today, she's had at least 12 wet/dirty diapers...so I assume she is getting enough to eat??? 

Starting this afternoon she's been wanting to feed about every hour for at least 20 minutes each time.  While she generally has a good latch, she's started head bobbing and tugging/pulling about 5-10 minutes after we start.  Is this associated with the let-down?  How do I know if I have a slow or fast let-down?  I was assuming I have a fast let-down, but maybe it's slow....I'm clueless!  Any suggestions?  

THANKS!