What Does This Ultrasound Report During Pregnancy Indicate?

hello Doctor, I had an ultrasound on 1/6/15 and found out i had a Single living intrauterine pregnancy with an age based on the crown-rump length of 6 weeks 3 days. I had another ultrasound on 1/20/15 and found the following Single intrauterine pregnancy with an age based on the crown rump length of       approximately 7 weeks 1 day. The expected age based on the prior ultrasound is 8 weeks 4 days and fetal motion and cardiac activity are not identified. The overall pattern is highly concerning for a nonviable pregnancy. I had been spotting throughout the whole pregnancy, even before my last ultrasound which was concerning. Today is 1/29/15 and i m only experiencing mild cramps and more spotting, nothing major. I know i have 3 options pill, d&c or natural miscarriage. I will prefer to wait for my body to take care of it on its own (naturally) however i don t know how much can i wait for the miscarriage to happen naturally before having any complications/infection/other issues. I appreciate your help and advise. Thank you,