3 month milestones

my LO will be 3months in two days, she was 3.6kg at birth(born at 39w via c section)

but not gaining much weight later(was only 4.3kg at 9w), i’m a first time

mom n as i don’t have breast milk she is exclusively formula fed…i’m paranoid each day thinking abt her weight, her head circumference,milestones etc😭😭 she is colicky and crying always, and absolutely no tummy time (cried bloody murder)can mammas to 3 month old babies here tell how heavy is your baby, HC and the milestones they have achieved? i know each baby is different, but i also want to know what to expect 😢