My 7 month old baby doesnt poop for more than 4 days now, is that okay?

I went pedia yesterday and my LO is 4 mths and haven't poo for fourdays, She says its normal coz I breastfeeding her, so usually baby will keep till 7 days. But not sure if your LO is eating something or not. But she adviced me to send her back if no poop for more than 7 days. So you can visit to pedia just to be safe