How To Regularize Period?

hello doctor, im priya.. im 24 yrs old and im single... i don get my mensus in a regular cycle. i face this problem mostky every month. even my cycle has delayed to the longest duration of about three months. but sometime i get regular periods. but once i get my periods tat entire seven days im normal and i don feel any complication. can u suggest a solution to this problem.im goin to get into my married life in short.. will this problem affetc my pregnancy. kindly give me a solution.