Bit of an odd boob question...

At the beginning of my pregnancy my boobs got bigger but now I'm 30 weeks and they have only gotten smaller. I think they may be smaller now than they were before I became pregnant. I've gained 17-ish pounds so I don't think it's due to possible weight loss. 
I'm just wondering if this has happened to anyone else? 
I'm also planning on trying to breastfeed and I'm hoping this isn't a bad sign. I tried breastfeeding my first son (he's 9 years old now) and was unsuccessful.