Am I crazy!

I'm 18, but since I was 14 my period has been super irregular. It would be non existent for up to 4 months, then I would get it for a day. Now, I get it twice a year- if I'm lucky three times. My doctor told me it isn't a big deal unless I go a whole year without it. But to me, that sounds bogus. I'm not trying to have children at this point in my life (obviously lol), but I'm afraid there could be an underlying problem that could effect me in the future. Am I being too paranoid? Should I just forget about it at this point?