What could be the reason for: late period, occasional cramping, & extremely sore breasts? I'm on birth control & I've taken 2 hpt, they were negative.

Birth Control! Actually, you may have answered your own question. There are different types of hormonal birth control. Some have estrogen and progestin, others just progestin. Both are capable of altering a cycle and causing sore bresats as your body "adapts" to the medication. It is usually nothing to stress about. Keep with your bc plans, and use it as directed. A negative preg test is reassurring.