Do Stress, Plan B And Nuvaring Delay Periods?

Hello, I had my last period which started on August 5. I was not on birth control and had sex just using the pull-out method. I took Plan B, on September 1 because I started worrying. I never had any spotting or bleeding from the plan B, nor did my period come. I have been under a tremendous amount of stress plus I was now worried about the chance of pregnancy. I took a pregnancy test on Sept. 13 and it was negative. Then on Sept 14, I started the Nuva ring, which I understand can delay a period. Last night, Sept. 21 I took out the Nuva ring (exactly one week from when I started it) because I just want my period to come. My symptoms are more related to PMS, Plan B and the Nuva Ring, rather than pregnancy signs. My period has usually come on time... however, my stress has been significant. I would like to know if you think stress, Plan B and having the Nuva Ring in for one week is the cause for my period being this delayed. Thank you in advance for your help.