My experience is more like Sassypant's: I started as a 34B, barely, before pregnancy. I was a 38B by the end of pregnancy, and I have no idea what I was for the first two months of breastfeeding, but I was wearing a Large in nursing bras. Then, I was a 36 D for a while, and by 8 months, I was a 34DD. I'm still a 34DD, and DS is almost 13 months. I have a feeling I'll be at this size for a while.
As far as tops, I bought new ones that are looser. None of my tops fit, so it seemed like the right solution. I found a style that I liked and got it in several colors. I should say, though, that I don't worry too much about what I wear or what's in style. I just like to be comfortable, even in my work clothes.