I too had mirena, it messes with your emotions and your body. You will spot after having it removed. Just let your body and hormones get back to normal then try again.
they say it normally takes up to a year to get pregnant after having it removed. and mirena has a dose of hormones so your body needs to adjust and get back to normal without it. how would you know if you are only a week pregnant? but anyway.. be patient you are probably going to spot until your cycle regulates