How can I make pleasure my breasts more fun?

This is probably gonna sound weird, but you could say I have boobs of steel. Like my breasts are nowhere near sensitive and maybe that's the problem or it could be fact that I go straight down when I masturbate? Anyway, I have double DD's and I want to have more fun with them? I want my nipples to erect and become sensitive. Help? Thanks in advanced! P.S I don't c*m when I masturbate, like when I orgasm (or think I am), clear liquid comes out but nothing else?