can you get pregnant after a D&C before you get your period? even if you still have hcg in your system?

Chanell
3 weeks after my D&C I had my post op appointment. They did a pregnancy test there and I had a very faint positive. The dr told me to test again in two weeks to be sure the hormone was out of my system. I wasn't planning on having unprotected sex before the 2 weeks were up! But things happen so I'm wondering is it possible to get pregnant again during this time?