Hey mama! NAN InfiniPro HA is pretty good, a few of us in our circle switched din from Similac at okay naman sa babies namin, though weight gain talaga depends sa overall intake and baby's metabolism pa rin. Since okay lang with pedia mo, I'd say monitor his weight gain at next check-up lang, pero since mix feeding kayo, make sure consistent lang the feeding schedule para makita mo properly kung kumakain siya ng enough. Some moms find their babies do well on it, pero it really varies eh, a couple weeks pa lang since you switched kaya baka still adjusting pa ang tummy ni bb, so give it a bit more time before you see steady gains. Good luck, mama!