OK. Well 5 ounces gain since Saturday is more than an ounce a day-so average to above average weight gain. But is this with supplementing 16 ounces a day?
Supplementing will make milk production decrease UNLESS you are pumping often enough with a good pump (hospital/rental grade if possible) to make up for the supplements. And sometimes even then.
How long do you pump each time you pump?
Could baby poasibly be encouraged to nurse more often-so maybe less pumping and supplements needed?
I wish you could talk to the IBCLC again. What if you called the appointment line? It is my understanding that before and after weight checks, while helpful, only provide limited information. It only tells you what happened at that one nursing session. Yes it is vitaly important that baby's weight gain get back on track. But it is also very important to not further undermine the breastfeeding relationship while doing so. It can be a very difficult balance and sometimes adjustments need to be made almost daily.
I almost hate to suggest a lactation aid because it is my hope you will be able to JUST nurse without supplements very, very soon. But here is the deal-basically there are two brands, the Medela SNS and the LactAid. Most mothers I know who have used them long term prefer the LactAid. Some mothers make thier own. It allows the baby to take in supplemental milk or formula via a tube while nursing at the breast. These are used most by mothers with low milk production and adoptive mothers. They can be tricky and messy and many moms hate them, but they definitely cause less breast refusal type issues due to bottles.
Here is an article about them http://www.nbci.ca/index.php?option=...tion&Itemid=17 On this page is a video of a 'home made' (clinic made rather) lactation aid being used. http://www.nbci.ca/index.php?option=...id=6&Itemid=13
Making More Milk is available online and is not expensive-12 or 15 dollars US. You local Library or your local LLL Group may have a copy to loan. You might find it at a well stocked bookstore.