Moaning or not.....

Question... when you have sex what triggers you to moan/scream!!! I'm a quiet person during sex and I'm so tired of my SO bitching about me not moaning!!!! It's every few days he says something. I wanna moan so bad but... (sad to say) but I don't know how?!?! I don't know how to get myself to do it and not "pretend" to do it vi have a low sex drive.. and I'm not to sensitive down there. Can anyone relate? Anyone have words of wisdom for me. I just wanna make him happy and make myself feel good. Thanks in advance.