please help!

Ladies, I have a 25 day cycle but don't know when I ovulate. My period was Jan 7-10th. I had sex one on the 12th and once on the 19th and I got a positive test on the 2nd. Which would be 3 weeks from the first day and 2 from the second. The first time seems way too soon for me to ovulate and too long for sperm to have lived. It's gotta be the second date right? Plus my test was pretty faint