first period after d&c? 4 weeks later and + hpt?!

Hey ladies, I'm not sure where to post this, but I am in need of some advice. I recently had a blighted ovum at 9 weeks and ended up having a d&c October 7th. It has now been 4 weeks as of November 4th. I've been having unprotected sex...is it possible to get pregnant right after d&c? Shouldn't my hormones be back to normal by now? The reason why I ask is because I'm assuming my period should be arriving soon, but has not yet. I just took a test and it looks like a very faint positive to me. But I know it's most likely leftover hormones and I've already had two miscarriages so far so I'm not getting my hopes up. For those of you who had a d&c, how long did it take for your test to show negative and for your period to return?