I'm 36 weeks and feeling rather toasty. I have a couple of strapless floaty dresses but the issue is I cannot wear a bra with them. Unless I put a t-shirt underneath which sort of defeats the object of keeping cool.
My boobs have grown but are not huge (32E) and are still perky enough that they are not resting on the bump (sorry TMI). I am completely happy having a day or 2 of bralessness as I'm just mooching about, not in work or anything but my mum was having kittens and suggesting that they will sag irreparably/have tissue damage 
so sane ladies of MN - to bra or not to bra??