DD1 would an 7-8 day between poo girl, she was topped up with S26 plain, and it was explosive runny poo, if her poos were forned or pellety I would say that she is constipated, but I am more of the thought that she is going into the occassional poosplosion phase.

If you do try another I would suggest staying away from Gold formula's, our Paed recommended doing this as the extra iron can cause constipation as well.
HTH's