I think its Implantation bleeding? Pregnant?

2 weeks before my period I cramped a little and bled a little, not even teaspoon worth. All the Ovulation calculators and pregnancy counters say that I wouldn't have ovulated till too late for my unprotected sex to get me pregnant. Yet the information Ive read says it Im actually right on the dot if I do the math myself. I have no other symptoms and it is still 9 days away from my period; my period has recently been right on the dot, except the occasional week late, couple days early and stuff in the last year or two. How long after implantation bleeding may I begin to feel other symptoms like sore breast which seem to be a constant among many pregnant women?

[LastHoldOut]

A Bit O Background. I had my last period Dec. 31- Jan 4. . . had sex the 9th,11, 12, 14, 15, and 20th(TMI). I cramped a little on the 21st at like 6pm, the next day I felt odd inside, not the feeling I get on my period. I had a little blood throughout the day that went away in the evening, and the next day a little brown discharge in the morning when I started work.