The seam up the back came a loose and there was a hole by my butt at my friends birthday party… cute dress cheaply made

I’m 5’2” 150lbs and I got a large, it was too big. When I first saw it I imagined a pink trash bag, but putting it on it does show off my curves still. The top is pretty loose and I’m a 34 DDD. I may be returning for a medium. The material is a little cheap but it still looks good on.