Question about D &C

I recently found out I had a miscarriage at 5 weeks, but still have positive pregnancy test and rising hormone levels. I’ve had multiple ultrasounds and in the beginning came out positive. This last ultrasound showed the sac but no baby. The sac measured to be 6 weeks and still growing, the reason they want me to have the D & C. How long can I go before I absolutely have to get the D&C; before it effects my body and other pregnancy?