No more fortifying with Enfacare

When we left the hospital until Tuesday my son's bottles were always fortified with Enfacare for Extra calories.  He never caught on the BFing so all bottles were fortified BM.  We were given the ok to stop fortifying on Monday.  He used to go about 3 hrs between feedings (sometimes 2.5 or 4).  Since we stopped fortifying he eats every 2 hrs.  He eats about 4.5 oz so he is getting over 30 oz a day!   Is this normal after stopping the fortifying?  It just seems like a lot and is hard to do stuff when he wants to eat every 2 hrs now.  How did your babies transition off the fortified milk?  Thanks