The first day of my last period was April 20th, 2012. I had unprotected sex May 3rd, 2012. I have not received my period. However on May 15th, 2012 I discovered I had left a tampon in, so it had been left for about 10-12 days but I am experiencing no symptoms of TSS. Also I have taken 2 pregnancy tests both coming up negative. Could the tampon be the source of my delayed period and should I go in and have a professional pregnancy test done?

First off, how do you leave an unnoticed tampon inside of you for that long? That may very well have something to do with your missed period. Just to make sure I would go into your doctor and have him do an internal examination to check for any sort of infection because you left a tampon inside of you for that long...