do u think I could be further along?

I know we aren't doctors here, but I was talking to my husband and something doesnt make sense. my app has me at 6weeks 2 days. but.... we only had sex when I ovulated in August the 16, 17, and 18th. I used opks to know. and I took my first pregnancy test on my birthday August 29th and got a positive on a cheapie and a digital. when I looked at my calendar that would have only been 11 or 12 days after I ovulated. my first ultrasound is on the 26th. do u guys think I could be further along? that just seems like a short amount of time to get a positive.