Itchy the sore/burning nipples

I am 17 me and my boyfriend do not use protection during sex my period has not come this month , but sometimes they are very off. My boyfriend has suspected that I'm preg. Because I have been eating a lot more, and sleeping a lot. Today my nipples started to itch really bad then followed by soreness/burning. I've taken a test and it was negative and I'm waiting to take another. I want to know if this is a sign of being preg. And if so what else I should look for