Can anyone help???

Okay so me and my partner are trying to conceive, I have regular periods that are between 9-11 days long. My cycle is 27 days long.

I have completely missed this month's period which has never happened before!! If I am late it's only ever by 1-2 days tops!!!!

My breasts are so sore and have been for nearly 2 weeks now. At first I thought I could be pregnant but I have taken 5 tests now last one being only 30 minutes ago and they all say negative. (Even tried different branded tests)

I'm so confused has anyone got any advice?