Pregnant?!

My last period was November 29th. I wasn't sure if it was really my period because it was very short & light. So I waited a few days and took a HP(it was negative). My fiance and I do not use any form of birth control and we have had sex at least once a week every week this month. AF was due a couples of days ago and has yet to show up. I've had symptoms like mood swings, cravings,& nausea. About a couple weeks ago I had some spotting.

How long should I wait before taking a test? Could I be pregnant? I'm just so nervous because I've had a MC before & I want the test to be positive.