Depo effectiveness ?

I mad a mistake and had unprotected sex with a woman that claimed to be on depo....once. She now is claiming to be pregnant but is still saying she was on depo. From the date she said she got the shot and we had sex was 11 weeks 2 days. I realize that is on the outside edge of the effective range but is it still in the 99% category at that point? I honestly doesn’t even know for sure if she REALLY is pregnant...she is just saying she is. But I want to possibly put myself at ease if my chances of getting this person pregnant are still in the 0.3% chance range.