First, it could be either. Having your doctor do a test will be much more accurate if you want to know for sure.
Stress, change in diet, exercise pattern, or sleep pattern can all affect your cycle. Weddings are stressful so it wouldn't be surprising if your body chemistry was a little off these days. The symptoms, or lack thereof, can be caused my many other things. Stress, for example, can cause appetite changes, and weight gain. Of course eating more than normal can add to weight gain too. Tender breasts are usually caused by hormone changes, but can also be caused by restrictive clothing, injury, or sex. As far as morning sickness, every pregnancy is different. Morning sickness or lack thereof alone is not an indicator either way.
False negative? Maybe. The best time to take a test is as soon as you wake up before you have had any food or drink that will dilute the hormone levels. Remember that home tests vary as to accuracy. Even the ones that say "5 days before your missed period" will not always tell you that soon. Home tests, on average, do not regularly come up as positive until 6-8 weeks. Check with your doctor, have a blood test done, and congratulations on your wedding!!!!