Fantasy is one thing. Were you to truly be taken against your will and involuntarily forced into this role you'd be singing a different tune. Fetishes and fantasies are fine, and healthy, just remember that's all they are. Many prostitutes and other people in the sex trade are sex slaves. There is nothing glamorous about it, in reality. Enjoy your fantasies, but keep yourself safe.
Yes, it's normal. you are a typical woman.
It's sick. It's fine to play at it during sexy times but the reality of living as a sex slave would be devastating.
so just do it; be submissive, look up dominatrix, i guess in your case you might need the male equivalent...totally normal though.