The pre­gnancy test and menstruation after taking nore­thindrone indicate you're like­ly not pregnant. Heavy blee­ding occurs frequently with this pill due to hormone­s. Though unlikely, pregnancy remains possible­ if periods persist irregularly. Monitor upcoming cycle­s closely, as flow intensity varies case­-by-case following medication. 

Vaginal bleeding of any kind might be a sign of many conditions like vaginal infection or cancer of the cervix. A gynecologic visit is necessary for an evaluation and correct diagnosis. If you have a blood-stained vaginal discharge, you need to see a gynecologist immediately.
 

You might be having signs of pregnancy, a medical condition like menstrual cycle irregularities or ovarian cysts affecting you. A gynecologist should be consulted for a detailed examination and correct treatment.

You are going through breast engorgement. This might occur when your breasts get loaded with milk and become sore and uncomfortable. As your body enters the process of your baby, it makes more milk hence your breasts become full very fast. Try warm compresses, gentle massage, and expressing some milk regularly to help with the discomfort.