Congrats on your pregnancy, mama! Yung milk production usually starts around weeks 2-4 after delivery, pero what you're feeling now, the firmness and tenderness, that's totally normal sa second trimester, kaya don't worry. The asymmetry (one side firmer than the other) happens sa maraming pregnant moms, a few of us experience it, pero it's always good to mention it sa OB mo sa next checkup just to be sure everything's okay, especially since you're noticing the difference. In the meantime, soft bras lang ang best para hindi irritating, at mag-rest ka ng maayos!