Suggest Treatment For Irregular Menstruation

hi, i am a 21 yr old woman and have had my menstral cycle for almost 6 yrs and its still not regular. i will go 2-4 months without a period at a time and occasionally will have a period consecutive months.nothing is regular with my period from time of month to how heavy my flow is to even how long i have one. my sister had troubles with cysist on her ovaries and has the factor 5 blood disease. i dont have insurance and havent ever been to a gynecologist, what could be causing my menstral issues?