Ladies help please!

Cortney
Hey ladies!! I was suppose to get my period on 7/13/14. It's now 7/17/14 and still no period. I am 4 days late. My cycle has always been 28-29 days never longer or shorter. Has came on time for years and years now. I know my fertile days and had sex multiple times each day in my fertile window including the day I ovulated, I have been dizzy, nauesous a little, very tired, headaches,  I have been bloated like crazy! Expecially at night, then goes away by morning. and has had ALOT of thick sticky creamy wet disharge for 2 weeks now. I took 1 test 1 week before missed AF - BFN! I took the 2nd one the day of my missed AF - BFN. I took the last one on 7/15/14, 2 days after missed AF and still BFN! :/ then the same day I started having period like symptoms: cramping, backache, lower pelvic pain.. But now after 2days of it that has stopped. I'm not sure if it's my period coming around the corner and it's just really late or may be that I'm pregnant. have any of you ladies missed your period had negative results and actually ended up being pregnant.  Sorry this is so long.  
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​Already a mommy to a beautiful girl! ?? would love to make her a big sister!