Overactive letdown?

jdp

So my 6 week old the past few days has only seemed to want to nurse for like 5 minutes, one side only.  And she also gulps like crazy and kind of squirms around and tugs the nipple, and latches on and off.  She is clearly getting enough to eat though because she has plenty of wet and dirty diapers.  I remember this with my first dd too, but not until later.  Is she this efficient already?  Is there anything I can do to slow the letdown?  I have an appt with pedi next week.