Hi So Before I Found Out I Was Pregnant I

hi so before i found out i was pregnant i would smoke medical marijuana, reason i say medical is because i had a prescription and ive an eating disorder so it would help me to get hungry & also to sleep.. anywas i stopped smoking when i found out i was pregnant, but at 17 weeks the dr couldnt find the babys heartbeat & the followinf week i had a miscarriage. & my question is, when exactly can i go back to smoking?