Four questions for period experts.

My period is three days late passed the estimated date and I usually am right on time, maybe plus or minus one day. 
I've only had sex once, we used a condom, he didn't cum.
I also traveled back to the U.S. From China(I was on my period then). I hear travel can make it late. 1) how late can that make it? What have you seen in your experience?Have you had this problem?
I've also recently begun exercising almost every day again. 2) can that influence it?
I lost my dog to cancer maybe a week ago and have been having to see new dogs and that has been stressful. Plus I've been stressed about the late period. 3) do you think stress is causing this?
4) do you think all the things above are affecting my period's timing?
FYI-I've been moody and have had some stomach pain, constipation. My breasts are a little sore as usually happens before period.