Feeling defeated...any suggestions?

Embracetheday

I'm feeling pretty defeated right now, as we just got back from my sons 4 mo appointment and he has gained only a slight amount of weight.  He's teetering on falling off the growth chart and I'm nervous its due to my supply.

I'm going to schedule an appointment with a lactation consultant, but want to do EVERYTHING I can to prepare for his next weigh-in a month from now.  I nursed my oldest for 14 months, so I'm confused as to what I may be doing.  I feel like I may have a decrease in supply and the only main thing I can think of that I'm doing differently is that I've really increased my exercise schedule.  I workout 6 days a week for about an hour each time.  4 out of those 6 days are intense cardio and the other 2 are pilates.  Is it possible that too much exercise is causing a tank in supply?  

Are there specific things that can hurt supply?  I drink regular coffee in the a.m. but lots of water otherwise.  

I guess I need to start doing anything I can to increase supply and get DS to nurse longer each session.  Anyone have tips? advice?!?