neg preg test but still feel preg

I am 37 yrs old. I have 3 children ages 12, 5, 2. I am ttc #4. I went to the dr for a pap in June and everything was fine. I even had an ultrasound to make sure their were no cyst. I was on micronor, but stopped taking them in jun. I had a normal cycle in August then 30 days later in Sept i had lite spotting for 3 day. (nothingover night and all day took to fill a mini pad) I have had bbt of 99 - 100 for 3 wks. My nipples are burning all the time. I want to sleep alot. I also have terrible head ackes. My cervix is closed and very wet. I know this sound like i am preg, but I have taken 3 tests and they all say neg. first respnce 2 wks ago, equate 1 week ago and anwer 2 days ago. I know with my daughters the test showed preg right away, but I cannot remember with my son. Ihave heard that boy hormones take longer to show up What do you guys think.