Well it was right at a year for me, but it does affect my supply; right before my period starts my supply dips. My supply comes back though, but the dip is frustrating, especially with the PMS that accompanies it!
My first was considerably light, but the next couple have been WOW so.so.heavy- like the first couple of days I need a tampon and a heavy pad to contain it while out in public. So yah, be prepared, just in case! lol