Hormone imbalance?

So my period is a week late. I haven't had sex in months so pregnancy is NOT something I'm worried about. I got my period in May on time and it was a normal period for me. This month I'm a week late with no signs of it coming. I've been dealing with cystic acne recently and I've read that it's a sign of hormonal imbalance. If I don't get my period next month I'm going to talk to my parents about going to see a doctor. I'm wondering what I can expect to happen at that appointment. What kind of tests will they be doing? If you have any advice I'd really appreciate it. Also how do I bring it up to my mom?