13 days late.....

Kayla

So I am 13 days late today, We have been ttc for 8 months now. I have been 10 days late before but only once & now I'm 13 days late. Ive taken 3 pregnancy test & they were all negative. My breast are super tender & my nipples are sore. I am completely lost. I dont know what is going on. Any advice/opinions? Please help!