Mira
I agree this baby needs supplementing with mom's milk or ABM. The baby needs
to be flooded with calories. I wonder if there is a urinary tract infection
(most common cause of low weight gain) or a hormonal problem.  It is hard to
tell if the baby's disorganized suck occurred. Because of the low weight gain
and low milk supply or if the low milk supply occurred because of the
disorganized suck.
If mom isn't comfortable with pumping: have you talked to her about manual
expression or comfort nursing? I can often talk a mom into nursing then giving
a bottle afterward by explaining that any breastmilk the baby gets is better
than none. If he improves his weight the suck usually improves as well.
Keep us informed.
Marie Davis, RN, IBCLC