A.!
I am so sorry you are feeling down about this but YOU ARE A WONDERFUL MOMMA AND JUST BY NURSING YOU ARE ALREADY DOING 100% MORE FOR YOUR CHILD THAN JUST FILLING HIS BELLY!!!!!!! Just because his weight is low MEANS NOTHING!!!!!!!!! Nursed babies are usually lower in the weight area than formula babies anyways. Is your son's length on the small side as well? You maybe just have a petite child or one that has not hit a growth spurt like most his age. I really would not worry as long as all else is well. "AVG" weight is too heavy............look at the "AVG" weight of someone your age and gendery today verses someone your age and gender 20 years ago. It is the same for babies as well. Weight charts are based on formula feed babies and formula fed babies weigh MORE, thus a possible start of the obesity epidemic! If your son is not hungry, he is most likely not needing the calories!
You said you have a great Lac. Consultant! Good! Great start! Have you considered joining La Leche League or a nursing support group as well? La Leche League is national and a great resource from active nursing moms! Also, talking to a second Lac. COnsultant can never hurt if you want/need confidence in what your first has been telling you. Lac Consultants at many govt hospitals (Harris Hosp for example) is free to anyone, not just those that deliver at that hospital.
Are you emptying each breast before going to the next? You may only need to feed with one breast at each feeding. Make sure to do this to empty out the hind milk (milk with most fat)! Fore-milk is mostly just watered down to quinch a thirst and hind milk is more fatty to fill the stomach. Use gentle massage from the base/inside of the breast out while your child is nursing (you do the masage, the child eats-LOL)! This will help empty milk sacs so the most hind-milk is received by the baby! Use gentle, flat pressure, not squeezing or agressive pushing: just a type of support to breast really, starting at the base of the breast (as close to the chest bone as possible) and slowly, with pressure, move towards the nipple then start repeat or start at another area at the base of the breast and repeat!
Also, are you making sure to drink water like mad? Tons of water will naturally up your milk production! You should AT LEAST drink half your weight in oz (ie: If you weigh 150 Lbs, 1/2 = 75 lbs, and that means you need 75 oz a day)! AND, drinking water at the beginning of your nursing session will help with your milk let-down!
Also, I suggest visiting your local health food/supplement store and speaking to a supplement specialist. They are very knowledgable about healthy, natural remedies and can help you with some other supplements to help your milk production and milk fat content!
I don't think supplementing with formula is a good idea, esp since your son is not used to it and has never had it. If you feel you must supplement, I would start with just a tad tiny bit of rice cereal, SPOON FED and just a tiny bit BUT you yourself said you don't think he is hungry after eating! All this would do IN MY OPINION is possibly prolong the time between feedings, thus not getting as many feedings in and as much breast milk. However, your son is 6 mos. now, so it is considered fine to do this (rice cereal) if he can hold his head up and support it well and you run out of other options. I would not go over-board and would only spoon feed so he will know the difference between liquid nutrition from a breast and solid nutrition. I would not mix it in with a bottle but i would use the breast milk to mix it up instead of water.......even if you can only express just enough breast milk for a tad bit of cereal at a time!
Best of luck! I know nursing can be hard. No one ever said it was easy.......BUT YOU ARE DOING WHAT IS BEST! DON'T LET YOUR SPIRITS GET LOW AND DON'T LET ANYONE SABOTAGE (sp?) YOU NURSING BY WISPERING FORMULA LIES AND "OH JUST GIVE UP" NOTHINGS IN YOUR EAR! IT IS LIKE A MARATHON AND YOU NEED THOSE CHEERING YOU ON!!!!!!!!!!!!! NOT THOSE TELLING YOU MAYBE IT WOULD BE BEST TO STOP OR CUT DOWN ON TRAINING (by using formula)!
Blessings!
T.