Overbearing MIL

So my MIL has been pushing me to start taking bump pictures. I'm 21 weeks along and I'm barely showing. I'm plus sized to begin with, but in the course of my pregnancy, I've lost about 15 pounds. Some days she'll look at me and tell me how pregnant I look and other days, primarily at work when I'm in uniform, I don't look pregnant at all. I'm slowing starting to tell a wider group of friends about my pregnancy and they don't believe that I'm as far along as I say I am because I'm barely showing. My MIL has been saying some things lately that have just rubbed me the wrong way. I mostly vent to my mom because if I try to vent to my husband, he immediately defends his mother. I don't know what to do. I feel like maybe I'm just being oversensitive, but I'm allowed to be....... right?