when should i take a pregnancy test?

I'm ttc, and i really think im pregnant. Me and my fiance have been having unprotected sex for almost a year now. and i had some bleeding on the 12th which only lasted 3 days, it was way lighter than my normal periods. So im guessing it was implantation bleeding. It was around the time I was supposed to get my period, though. So when would I be able to get the most accurate results with a hpt?

Thanks in advance, I would figure this out myself, but i've got a lot on my mind right now :)

** I have a lot of other signs too, just so you know.

Nausea, headaches, breast pain, mood swings, always hungry, fatigue, Light cramps (barely), gas.