Baby constipation

My daughter is 16 weeks old and has been EFF since birth. She’s always done 1 poo a week (which the GP wasn’t fussed about at her 6 week check up!) but she has always cried when pooing and recently her poo has been hard and baby is constipated.

Has anyone else experienced this/ will she ever not have awful poo’s she’s often bright red and so upset and I’m worried because whenever I research websites say it takes babies a few weeks to get used to digesting formula but she’s been having it since birth and has only ever pooed once a week. Loads of my friends babies poo multiple times a day and everyone is always shocked when I tell them she poo’s once a week! She’s gaining weight and is on the 75th percentile! I’m not sure if it’s the formula ? We use cow and gate - or if it’s just completely normal for EFF babies?

Will this get better when she’s on solids? Will it get better on its own? Has anyone else had a similar experience ?

I might call the GP again to get it checked! Thanks :)