Pregnant or late period?

Sie

My last period was Aug 6-Aug 12th, I then had sex on the 17th(no sex since then) My period was due Sept 4th.

I am 11 days late. I took a test on the 9th, it was negative; I took one today(15th) it was also negative.

I did notice today my nipples are very sore. No other symptoms besides body aches.

Would it be safe to say I'm not pregnant? I would think by now (6wks since last period) that if I was, a positive would appear?