Definitely not a bragging post!!!

Ok so I'm currently 7 months pregnant, (27 weeks) that's what this app and my lmp tells me and I haven't gained not one single pound! I'm concerned that it may be an issue but it's weird because I look very absolutely pregnant. I did change my eating habits but it wasn't particularly because I wanted to or I was concious about being more healthy; I just craved every vegetable and fruit known to man. Lots of salads, California rolls, no fried foods or fast foods cuz they made me nauseous and tons of water since juice makes me nauseous also. I'm going to the doctor on Thursday but I guess I'm just a bit nervous that they're going to tell me I need to start gaining weight. Right now I'm 218, that was my prepregnacy weight and I'm 5'4 tall so I know my BMI is pretty high. I'm just not sure if it's healthy to not gain weight even though I'm eating every 15 minutes it seems. I just can't stomach a lot of heavy dishes, mostly carbs & all the stuff I used to love and while I feel better, I'm not particularly sure that's a good thing for baby. Any tips or advice?