Hello and welcome to Healthcare Magic. Thanks for your query. It appears that you may be a hormonal imbalance which is causing you all these symptoms. Irregular or delayed periods are indicative that there is a hormonal imbalance in your body and this could also be the reason for your symptoms such as sore nipples, bloated sensation, low back pain , etc. One of the common causes of this hormonal imbalance leading to irregular periods is a condition called Dysfunctional Uterine Bleeding (DUB). The reason why you had been getting regular periods when on birth control pills is that, they contain hormones which normalize this imbalance. In fact, birth control pills are prescribed for the treatment of DUB. Another possibility for irregular or delayed periods is a Polycystic Ovarian Disease (PCOD) - this is characterised by the presence of multiple cysts in the ovary and other prblems like obesity, unwanted facial hair and often infertility. I would suggest that you have a detailed evaluation by a gynecologist to determine the cause of your irregular periods. Sometimes, a short course of hormonal medication (containing the hormone progesterone) is given to induce menstrual bleeding. Also, if you are overweight or obese, then regular physical exercise and diet control is also important and can help in regularizing your periods. Wish you all the best. Regards, Dr. Sheeba Stephen