Thanks to my MIL I no longer have any self esteem

So this whole pregnancy has been crazy dealing with my future MIL. We moved out of her house because she wanted to pretty much raise our child and do things her way so thankfully we have our own place now and don't have to worry about it. Now I am a pretty petite girl, always have been. She's a little on the larger side and this whole pregnancy I've literally just been all belly. I'm 34 weeks and have gained 17 pounds total so far. I'm due in march. We went over there for dinner earlier and my SO was talking about how I ordered a bikini last month for our summer vacation which we all take together. I also proceeded to talk about all the things I'm going to do to lose the baby weight before the end of June because  our vacations in July and she flat out told me I must be delerious if I think I'm gonna be able to fit into a bikini by then. I'm normally 132 pounds and mostly all of that is muscle. I am so self conscious it's not even funny and she is constantly bringing me down like this. I'm 21 years old,   So you guys think I'll be able to get back to me prepregnancy weight by the end of June? That'll be 3 whole months and I plan on breast feeding and working out lightly until I can handle more as well as eating a healthy nutritional diet that will support me and the baby as I will be her main source of food.