With your period not being due for another week it's still possible that you could be pg. With a 28 day cycle you probably would have ovulated the 6th with your most fertile days being the 3rd-8th. Pulling out does nothing...semen leaks from the penis throughout intercourse and it contains sperm.
11th-12th could have been implantation...cramping is common around that time. It happens 5-12 days after conception.
Today would be too early even with the most sensitive pg test to get a positive. The earliest I've gotten a positive is 8 days past ovulation and the latest is 3wks past ovulation. So until you miss your period a negative pg test may not mean that you aren't pg just that your pg hormone levels aren't elevated enough yet to get a positive.
Nope, it's not too early to have symptoms...I've had symptoms as early as a week before my period was due

. Once implantation happens your hormones go a little bit crazy and it can cause you to experience a wide array of early pg symptoms.
All this isn't to say you *are* pg just that it seems to still be a possibility based on the dates you provided
Hope everything turns out well!!! I know being pg when you would rather not be is a scary thought

(((HUG)))!
Take Care!