Re: When did your boobs start getting bigger?
Mine grew at the beginning. I started as a 34A and busted out of those by week 9 or 10. I've been wearing sports bras...which I highly recommend...especially the ones that stretch to accommodate multiple cup sizes. They offer great support and are fairly comfortable to wear to bed. Plus, they stretch with you, so you can wear them longer into your pregnancy before they don't fit anymore. I got several cheapies at Wal-Mart for about $4-$5 each, and they are holding up fine.
I ended up buying 1 real bra around week 15 or so because the sports bras have the tank top effect and didn't allow me to wear a lot in deeper v-necks. That real bra was size 36 nearly C (one of those half-sizes).
Now, at 23 weeks, I'm going to need another real bra...I'm sure I'm well into the C if not almost a D. Interestingly enough...I'm still wearing all the sports bras I bought initially. I save the "real" bra for certain outfits, and plan to wear the sports bras until they are worn out.
I think doing it this way has saved me plenty of $$ in bras in the long run.