Sorry - this is a bit personal! 
Yesterday I was moaning about the terrible four boobs I was having. Today I put the same bra on (don't usually but it was only for five minutes while I nipped out) and I could have fitted my phone in there. I had checked it hadn't folded or anything to reduce space yesterday and I was sitting properly both days.
I'm used to a bit of variance over the month but this in 24 hours is ridiculous! Not to mention makes clothes shopping hard.... I don't imagine I should worry about it but is this level of flux normal?
Thanks.