Super Irregular!?

My period is EXTREMELY irregular. I'm 16 and when I got my very first period it was around the 25 of May... Now, it's been around the 4th of every month and sometimes I miss a whole month and a half and I'll get it again at a conepletely different time. In the beginning of 2016 I didn't get my period at all that year until the end of March. Is there anyway to fix this? It would be nice to know so I don't keep getting embarrassed in public.