Hai! Actually memang boleh normal saja, a few of my mum friends yang fully breastfed, their babies pun ada jugak yang boleh tak berak sampai 7-10 hari especially around 3-4 months, sebab breastmilk very efficient, so less waste. Since your baby's tummy is soft, dia kentut okay, and active looking, that's a good sign lah. Tapi kalau you're worried or nampak baby uncomfortable in any way (like struggling or crying when trying to poop), better check dengan doctor je untuk peace of mind, they can give you a proper assessment. All the best!