Some women never have regular periods. You are right though, since you started your period when you were thirteen, and it’s been two years, if you were going to be regular it should have typically been so by now. What matters more is whether you were regular for any length of time (more than 6-9 months) before becoming irregular. I suspect you haven't yet had a “regular” stretch, although going six months without your period is a long time. In general, if you go for more than three months without your menstrual period it may be time for a healthcare provider to step in. Talk to your parents about seeing a different provider or going together to see your current doctor and talk frankly about your concerns.
It is common for periods to be irregular when you're young, but six months is long enough that you should be addressing this with a healthcare professional. I'm sorry to hear that you feel your doctor doesn't care. Have you seen a gynecologist yet? If not, talk to your parent or guardian and make an appointment with a gynecologist. The American College of Obstetricians and Gynecologists recommend that you have your first gynecologist appointment between the ages of 13 and 15, anyway. I'm sure that a gynecologist — male or female — will care that you've missed six months worth of periods and will help determine if there is an issue or not.
It does take a couple years for your period to find its pattern, although I’m not very sure about it stopping completely. As for the doctor, my recommendation is if you’re not comfortable with him, ask your parents to take you to another. You should be totally comfortable with and trust your doctor! Also, check out what Dr. Molly has to say on this. I bet she has a good answer!