I don't have a regular period and when it comes my nipples are never sore and sensative. But this last week they have been very sore. Why is this?

Your bodys hormones don't sound like they are very balanced... if you are sure your not pregnant (as this could possibly be a symptom) then I would think about consulting your doctor about going on the pill, it will regulate your period and hopefully stop your nipples from getting sore!. good luck!