2 weeks late

I am almost 2 weeks late, I will be on Monday, I have taken 2 tests earlier last week that both came back negative. A few days later I started spotting it it was VERY faint, I wouldn't have noticed if I wasn't looking for signs of aunt flow. That lasted about 4 days, officially stopped spotting yesterday. I'm wondering if that could have been implantation bleeding. If it was, when should I test again? I don't want to test too soon but I want to know.