Implantation or AF

So I have been trying to conceive for 3 months and not last Friday but the one before I started having light bleeding 3 days before AF was due and the bleeding was light for 2 days. Thinking It was implantation bleeding I took a test 3 days later and got a bfn but was wondering if that was to early to test as since then I have been nausea and have severe headaches and was wondering if there could still be a chance I could get a bfp?