Not gaining weight?

Hi! I'm a first time mom and I don't know a lot of stuff, but there is one thing that is worrying me. I am overweight, and I am 14 weeks pregnant but I have not put up not even a pound. I've actually lost a pound. I know first trimester was hard on my stomach and I could barely eat anything, but it has been 3 weeks that I've felt constantly hungry and I have eaten when I feel hungry. The only food changes I made was to go pescatarian, eat more fruits as snacks and more veggies. I have not exercised at all. So how haven't I put any weight and is that safe for the baby? My OBGYN is good for nothing really. So anyone who has had similar experience? Anyway, thanks for reading and blessings!