Hi, I'm 26 years old and have missed my periond this month. I have taken two pregancy tests and both came back negative. I don't believe that I'm pregnant because I have had two kids already and both times I was pregnant I knew before I even took the tests, and I don't feel pregnant. But I'm not sure what is the matter with me then. After I had my last baby this past August my periods have been pretty light, could it just be that I just am going to miss it this month?

There are a lot of things that can throw your cycle out of whack, stress, medicines, illness...
Could any of these factors contribute?
If you are worried go to your GP to get a check-up :)