Mine were never "killing me" but they were pretty sore off and on from weeks 6-9, especially when touched. Now they're not too bad except in the morning they're sore when I first get up, like they're heavier but they don't feel like it during the day.
Downside is, once the boob soreness went down, I got full blown morning sickness. My symptoms tend to trade off dominance week-to-week. I think I'm the odd one out there though, lol.