Possibly pregnant ?

Mother Nature was supposed to make her entrance between AUG 14-16. She still has not arrived. I took a test on the 15th and it came back a very faint positive(noticeable but not super bold) and I took another one the 20th and it came back negative. Could it be too early? I can’t figure out what is going on. If I am, today I would be 5w1d. It would be my second. I’ve had no signs of aunt flow. Just nausea all month. Opinions???