Pregnancy books tell you that you should sing to your baby because your baby will love your voice, no matter what you sound like. Big fat lie. (The lies that pregnancy books tell you will be a topic for an upcoming blog post, I'm sure.) Your singing may drown out your baby, but if you can't carry a tune, it's not going to be a peaceful night for anyone.
Disney Princesses are the WORST role model for your son to have. Here's my advice. Tell your son it's okay to be a princess for now. But one day, if he wants to rule, he'll need to step up and become a queen. And being regal means NOT getting co-opted into the princess-industrial complex.