Faint positive after miscarriage

I miscarried December 9 and only bled for a week (I was only 6 weeks at the time). I got my hcg checked and it went down to zero and did a follow up ultrasound on the 23rd to ensure everything cleared. There was also a new egg ready to go... I just got this yesterday and am scared since my ob told me to wait a cycle before trying again. Is it true it’s high risk to miscarry again?