Should my boobs be doing something?

Esmerelda
I'm 30+5 and my friend who is 31+4 has had leaking boobs for weeks now.
I had some tenderness in the early weeks of pregnancy but have had nothing since. They are a little bigger but not much and there is no tenderness or leaking at all! Anyone know if that's normal? 
I've always been quite flat chested and I'm worried I won't produce milk. I know everyone says that size doesn't matter but it's hard not to wonder as it just feels like something should be happening.