Plus size mommies

So I have pcos and had lost 15lbs and was actually able to get pregnant naturally after having to use fertility meds for my last child. Anyway. The first picture is after I had lost all that and the second is me now at 15 weeks. I haven't gained any weight at all I've actually lost an additional 1-2lbs depending on the day.  So why does it look like i swallowed a watermelon so early? Maybe because it's my third child I'm getting bigger sooner? Anyways I feel like a cow lol.