worried...I might be pregnant. help! please

So, my boobs and nipples hurt and are so sore and tender I can barely even touch them. I've taken two pregnancy tests but they've come back negative. If I am I think I would be like 3-4 weeks at least and maybe 5-6 at most. I had a period in October that lasted a full week and was kinda medium in how much blood came out. Had to change my regular tampax pearl tampons around every 4-5 hours. I'm not sure what I should do now.