Could Delayed Periods Along With Sore Breasts Be The Symptoms Of Pregnancy?

I and a 32 year old mother of 5 children. My first and second pregnancy, (both girls), were both very healthy, no bleeding, no complications, full term 39 weeks, both vaginal. My 3rd pregnancy, (boy), bleeding began at 14 weeks gestation, and continued on and off, for the remaining of my pregnancy, and he was born very healthy, at 33 weeks gestation, by cesarean section. My 4th pregnancy, (boy), was a completely different story, starts as the normal, missed period, and then a positive pregnancy test at approximately 7 weeks gestation. Within days of finding out that I am pregnant, just a few days after a positive pregnancy test, I began gushing blood very heavily, and assuming I was having a very early miscarrhave. I get an ultrasound immediately at the hospital, which revealed the baby was still alive, and had a very strong heart beat, and no miscarriage. No placental previa, but in fact, was a subchorionic bleed/placental abruption. I was told the pregnancy probably would not last much longer, and that it would still end up and a miscarriage, but despite all odds, the bleeding continued daily, for the remaining of my pregnancy, and on September 3, 2009, at 12:02AM, my baby boy was born at 24 weeks gestation, with no heartbeat, and once again, against all odds, a miracle, my baby boy was resuscitated at 12:54AM, after approximately 52 minutes of CPR. He spent 7 months in the NICU before coming home for the very first time, and to this day, he is a very healthy boy, no birth defects, PERFECT. My 5th pregnancy, (girl), most recent, and so far, my last pregnancy, was very healthy, no complications what so ever, no bleeding, born on January 6th, 2014, full term at 39 weeks, and cesarean section as well, which was 3 cesareans in a row, (3rd, 4th, and 5th). With all 5 pregnancies, I had a positive pregnancy test very quickly after missed period. My question is, is there any health issues, or any reason that a pregnancy test will show a false negative, in the second or third trimester??? Obviously I have been pregnant 5 times before, and know the feeling of fetal movement/feeling a baby move, and for the last month, I have been feeling very strong movements in my belly, all over the place, sometimes faint, dull, but mostly very very strong kicks, on a daily basis, 7 days a week now. Both breasts are swollen and leaking breast milk, and have the white dots around the areolas, and that was actually the first symptom I noticed, that led me to believe I could possibly be pregnant with my sixth, but I have taken about 7 different urine pregnancy tests in the last 2 months, and they are ALL, 100% negative. I am definitely feeling movement, and it is definitely not gas, these are real strong kicks, so if I am pregnant with my sixth, which I am very strongly convinced, and I am almost 99 percent sure that I am, so why are my pregnancy tests, ALL coming out completely negative??? I am very confused.