Would a test show me a positive by now if I was really Preggo?

So my periods are not regular. But would a test show me a accurate answer 4.5 weeks after I last had u protected sex? Would that be plenty of time to give a accurate answer? I did bleed earlier in the month which I get nervous it was implantation. But still that would be like 3 weeks after the implantation bleeding too. Would a test give me a accurate answer by then? Thank you al