For the last two nights, when I wake up for middle of night feeding (after 5-6 hours) my left breast is hard and large and my right breast is softer and smaller. My 6-week old daughter still gets milk from it, but I'm worried the supply might be dwindling there. What could cause that and how do I handle it? I switch the starting breast with each feeding, but she usually drinks well from both. Also, I pumped both sides right after the 9 p.m. feeding.