Is it okay to talk to my doctor about this?

I am seventeen (eighteen in a week) and I am a little concerned about my sexual health. I have an extremely low sex drive despite having been in a relationship for eight months with someone I love and trust. I have looked online for possible causes, and I am a little worried that I may have some time of hormonal disorder. In addition to a low sex drive, I have extremely irregular periods. My physical is tomorrow, how should I approach the subject with my doctor? I'm I just unnecessarily worried?