Late Period/Early Period/No Period

Ok--I'm on a 28 day cycyle and my last period was due around 7/10, but I got it early on 7/5. I normally have clockwork cycles and my periods are always on time. Well, on my regular cycle I should have gotten my period around 7/25, and on the early period schedule my AF should have come around 8/1. My hubby and I had on 6/28 during my June ovulation cycle, and 7/27, which would have been my ovulation cycle based on my normal schedule. On a few occasions, I have dry heaved in the afternoon, but this has only happened a couple of times. I'm still exercising 5 days a week, and it ranges from moderate to hard depending on my mood. I usually drink 1 gallon of water a day, etc. No weird food cravings, no tenderness, no bloating, no PMS symptoms, nothing! The only thing I can see is that my l discharge is similar to the ovulation discharge...it's been this way for a couple of weeks, which is strange. Oh, and yes, I've taken early pregnancy tests for the past two weeks and all have been negative. I don't know what's going on...am I pregnant or what? I appreciate your feedback. Thanks!