Hello, No, your chances of getting pregnant is low. Morning after pill is very effectively if taken in time and as instructed. The pain that you are experiencing in the breasts may be due to hormonal imbalance due to the medicine you took. Other medical conditions that may cause pain in the breasts are breast cyst, mastitis (breast infection), it can be pain from the chest wall like inflammation around the ribs, bone fracture, etc. Wear a comfortable, supportive bra. Take low fat diet, avoid smoking, caffeine, restrict salt in take. Get clinically examined by a gynecologist, get your breasts examined to rule out any infection, cyst or lumps. If needed you will have to get done mammogram and other required tests and investigations. If you develop symptoms of early pregnancy, get pregnancy test done. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician