Passing motions 3-4 times in a day is common at this age and normal also! Need to know whether it's loose stools or normal consistency. Usually if feeding well and passing urine well, baby is playful, there should not be any issue, though physical examination adds on to further clues. Can click to call and discuss if problem persists

Passing frequent motion is very much normal on breast feeding and may be around 7-8 times a day but as u have noticed only when it is on formula feeding why give formula at all please try to exclusive breast feed the child which has more advantages than intermittent formula feeding if u feel the baby is passing urine 6-7 times a day and is gaining weight than ur lactating well enough and their is no need to give lactogen