Why did I take it today? BFN sadness

I just took a pregnancy test this morning bfn. I have been having what I thought were all the symptoms, and this time they were different. They included sore breasts, feeling weird and off, and even big huge mood swings that I don't even know I'm on my period. I have cramps, I just feel really different. AF is due 9/21 but on my Glow list today and said I could take the test. Even the thread it's attached to explain that I should wait till I'm missing my period. I am just really sad. I just always think I'm pregnant take please find out I'm not pregnant and then my body follow suit. I thought this time was different. I really have loved reading all of the threads on Glow because it makes me feel less crazy.