your boy's weight is at the 25%. as far as I know, if your baby is eating well, sufficient soiled diaper and also not losing weight, it is not a concern. I have 6 kid and they all grow differently. if you are worry, do highlight to them during your baby's appt.
I would refer to the health booklet instead of 3rd party app. growth happens in "leaps" instead of a steadily growing daily. wait for the next leap!