I'm not sure about the wanting to be a child feelings, but the way you describe your thoughts about sex and how you feel about it with your husband makes me think of myself. I identify my sexual orientation as asexual which means I lack sexual attraction to anyone (even though I still find men to be aesthetically attractive..cute, hot, etc.). I have no wish to have sex with them or do sexual things with them however. Maybe read a bit on asexuality and see if it fits you?