Stress can cause a delay in one's cycle. If the body is under physical and/or psychological stress...then the reproductive system takes a backseat to other more crucial functions.
Your travel and disruption in sleep and routine could have just added to the issue.
Still, if you've still not started in a week, I would consider going to your OBGYN again for another blood test.
Try doing some consistent coping skills the next few days to decompress.
Peace and progress,
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT