Pregnant again right after miscarriage

Caitlin • Jacksons mommy 8/29/16. Braxton's mommy 1/31/18.
So I think I'm pregnant again and it's only been 3 weeks since my miscarriage. My doctor told me to wait so my body could heal just one cycle. But I was only 6 weeks along when I miscarried and did not have to get a d&c so it was very similar to a period. Is it possible to get pregnant again this quickly? Will I be more at risk for another miscarriage?