I've had similar cycles, ranging for 28 days just recently to 36 days two months ago. As sherrycoup mentioned, stress, travel, sickness, new medication, etc. can delay ovulation thereby delaying AF.
The light spotting that you experienced could have been breakthrough bleeding caused by the cervix getting hit during intercourse. It happens every now and then. The pregnancy symptoms you're feeling can be so confusing, because they're the same symptoms of when AF visits.