5-6 months Irregular Periods

I'm 21 years old and have had the most irregular periods! They've always been a few months apart (5-6 months apart), and it seems to be less and less every time. This time is the longest I've gone without my period at 7 months!! 
Does anyone else experience anything like this? I'm hoping to have children in the future and am very scared that I might becoming infertile or something :(