Baby #2 isn't that big?

Ruth

So this is my second pregnancy and I noticed that I'm not as big as I was with my first and I'm having a girl again. Has this happened to anyone before. It basically looks like I just gain a little bit of weight and next week I'll be 20 weeks already. My husband teases me because when he wants to touch my belly it's so small and he says where is it? Lol is this normal?