Baby not pooing

I have just recovered today from a short lived round of mastitis.

My baby is 7 weeks old and has not had a bowel movement for 3 days now. She is still producing wet nappies but not as frequently as before. I am often as often as before (if not more)

Should I be worried? How long can a baby her age go without pooing? I just don't know if I should take her to the doctors (takes at least 3 days advance booking to see her gp so if it's urgent I'll have to take her to the Er).