I want to regulate my menstrual cycle..it's...

How to treat Irregular period 
As you already know that irregular periods affect you in a bad way and lead to pregnancy problems and it can be treated by maintaining a healthy life style by exercising more , losing the excess weight and reducing stress , but if the problem was as a result of PCO , you should start Glucophage in addition to OCPs , doctor will prescribe you a drug such as Levothyroxin in case of hypothyroidism . you also have to know that sometimes it's normal to have irregular period in cas of approaching menopause age or in the ver begining of puberty 
What investigations must be done ?
to Diagnose PCO , you have to measure ovulation hormones such as FSH , LH , as well as U/S to the uterus and ovaries that will show presence of cysts , and if thyroid problems are suspected you can dignose by TSH T3 T4 
What are the causes of Irregular period ?
Polycystic ovary 
hypothyrodism 
Prolactinemia 
normal pysiology in cas of puberty and menopause 
OCP 
IUD
Advice :
You have to have a visit to gynacologist