Slight headaches/tired/QUESTIONS?

so long story short im on a very affective birth control... and there's a very very very slight chance. I could be pregnant. I think I experienced implantation bleeding a few days ago. and since then I've been tired all the time. have gotten headaches I normally don't get and been peeing often. and a little hungry almost all day. could I really be pregnant? :/ and when should I take a test? ?