15 days late

So Im 15 days late on a perfect cycle. 11 days late on a month long cycle. I had my period in October from 8-13. Used withdrawal method the whole time afterwards. Had intercourse quite a bit. Hubby just deployed. I've taken 3 urine pregnancy test and all negative. I've had headaches and my boobs hurt so bad that going down steps is uncomfortable. This morning I had slight brown discharge. Am I pregnant? Is it too early? Is it stress? My cycle is never never off.