Not gaining weight.

Ever since I've been pregnant I have been loosing weight not gaining. Which I know it's not bad I just don't understand why. Before I got pregnant I weight 221 and now I weigh 210 maybe even less idk if I've lost more the past few weeks but that's what it was at, at my last appointment, I go back Monday. And I haven't been getting sick since I've been in my second trimester and trust me I eat.