Hello Sparkles, my heart goes out to you as I know how worrying lack of weight gain can be (we have also experienced but when DS was around 4 months). You don't mention where in NSW you are but if you are in Newcastle/Hunter area I can recommend and excellent Lactation Consultant who helped us.

Private Message me if you want her details.

btw....I did the same as you with expressing after feeds, I did this about four times a day plus fed about 10 times a day and after two weeks my supply is definitely up and DS is gaining well. I am still feeding about 10 times a day (DS is now 5 months + 5 days) but no longer expressing. I didn't top up with formula but I guess it is different with a very new baby. Also as Kmn mentioned there could be other factors so best to consult an expert. The most important thing I can offer is to listen to your Mummy instincts. We sought expert advice from LC & Paediatrician which was brilliant (esp. LC) but I did what I thought was right & guess what...it worked!