No weight gain?

Kasia • Happy momma to one perfect little boy 💙 M. 22/08/19 💕 Baby #2 due in March 💕✨

I’m 15 weeks today. All the apps are saying I should gain around 5kg/11 lbs by now I didn’t put on any weight. Like literally NOTHING. The bump is slowly getting bigger, I’m starting to look pregnant and the baby is healthy and growing perfectly. Should I be worried I’m not gaining any weight..?