I don't understand the fear of having any amount of testosterone in your system in the MtF crowd.
Your body needs a bit of it, it's completely normal for all women to have a little bit of it. It helps prevent osteoporosis, regulates some aspects of brain function, and more. Freaking out because your blood test results are higher than zero is just silly. Obviously you don't want to be in the normal male range, but a level of zero is not a good thing either.