Wedding/pregnant

Hey you guys. Okay so me and fiancé are getting married but here is the crazy part.. He proposed to me in late January. So in march.. I found out I am pregnant!!! Our wedding is in June 25. Right now i am 7 weeks. When my wedding comes I'll be 4 months. Idk how big will I get. I'm so nervous because I have my dress. It's a size 8. I'm worried about belly room. Right now there is a little room for belly. Idk how big will I be at 4 month! Will a girdle/corset harm my baby?