First off...don't let your family/friends comments scare you.
I am 25...started my period when I was around 13 or so and still NEVER have regular periods. In highschool my doctor said it was because I was so active in sports, my body fat was so low that it interfered with my period...they saw no problem, and I was young I wasn't upset that I didn't have periods....less to mess with!!

I actually could somewhat control them....if I started to spot, I could go out and run, and totally skip a period!
When I left for college my doctor put me on birth control pills to regulate my periods. That worked for awhile, then even that keep them coming. I actually got pregnant with my daughter after not having a period for about 3-6 months, AND I was on the pill!
After I had my daughter I didn't have any periods unless I was on some sort of BC meds. When I wasn't sexually active, I stopped all BC meds and didn't have a period for about 2 years. I went to the doctor about a year ago, because me and fiance (at the time, now my husband) were trying to get pregnant. My doctor said all my hormones were fine, and really couldn't explain why I still didn't have periods. She put me on Prometrium, which let me have a few periods, and regulated me.
So as you can see, irregular periods are quite common, and usually nothing to worry about unless you are trying to get pregnant.
As soon as you became sexually active, though, you should always have a yearly pap smear. It's really not as bad as most first-timers think. My OB said, although, there seems to be nothing medically wrong with me, it's not normal to go more than a few months without a period.
You need to have a pap done....it will ease you mind, and you can discuss with your doctor about medications that can regulate your period
