Hi Doctor Yesterday I Did Transvaginal Ultrasound. Before That Supposedly

hi doctor yesterday i did transvaginal ultrasound. before that supposedly if follow my last date of menses im 7+2 days pregnant. but yest the ultrasound measure as 5-6wks plus. & the baby sac only have bubble ring & no fetal no heartbeat. currently im spotting for almost 4-5 days before yest check up. Dr prescribed me with duphaston. is it works to stop spotting? coz after 2 tablet taken still the same & i have slight cramps here. is it a early signal of miscarriage coz no yolk sac? i have miscarriage on march 2016 if i miscarriage again will be my 2nd times. what should i do now?