AF is Late....

Elizabeth • Student and former nanny and daycare attendant. Just making my way through the world learning and teaching
AF was due the 23rd and hasn't shown up and I've got no signs of her coming. My boobs aren't super tender but they're slightly tender....they itch more than they hurt. They're spilling out of my bra!!! I have been a 36 DDD since my senior year in high school and these bad boys NEVER swell up like this....I eat everything in sight, I've got some mild back aches and tummy cramps (not like cramps I'm used to around AF). I'm tired all the time but have insomnia which makes it hard to fall asleep, certain smells and foods make me nauseous and certain foods I just can't get enough of. 
I have taken 4 pregnancy tests and all were negative....I'm afraid to go to my doctor and get a blood test done. I don't want it to be negative and find out that something else is going on. I have anxiety over trips to the doctors.
If my 4 HPT were negative is there a chance I'm still pregnant and just producing hormone levels that are too low for the tests?