Missed period.

I was suppose to start my period on 10/14/17. I've taken multiple test, and there saying negative. People keep telling me my missed period could be caused from stress, but ivebeen stressed my whole life, even worse before than now, and still never missed my period. I'm not sure why test are giving me a negative when I'm now 6 days late. I took clear blue test. Any advice on what steps I should take now... me and my boyfriend have been planning.. I woke up this morning and my nipples were super sensitive, and my boyfriend rolled over and grabbed my Brest, (we sleep naked together) and he said your boobs feel really swollen this morning.