If you are 12 days late it should show on a test by now you could wait a couple more days and take another test just to be sure but if that comes up negative you most likley are not pregnant then. But you should call your doctor and ask for a blood test to be 100% sure. Some woman think or want to be pregnant so bad they get all the symptoms and miss a period and are not even pregnant happened to me once so I know how easy it can be to trick your body into that sort of thing so try and not do that to yourself.