I have kind of an odd question... I've never had small boobs, & now that I'm 6 months I've noticed…

I have kind of an odd question... I've never had small boobs, & now that I'm 6 months I've noticed that they're leaking or lactating? I'm not sure what it's called when it happens while you're pregnant.

Anyway I've noticed that my boobs are starting to feel hard, if that makes sense. Is that normal? No pain or anything like that.