Hi, my girlfriend lives overseas and she's on depo provera. She gets the shot once or twice a year only (not every 12 or 13 weeks). She has it injected one month in advance, every time before I travel overseas to visit her and have sex. I know depo provera meant to provide over 99% protection after 7 days, but we like to be extra cautious and wait a month before having sex. She had her last shot in September, and I visited her nearly a month later in October.
Now it's nearly December, and today she took a home pregnancy test which showed up with a positive result. Given that depo has such a high protection rate when used correctly, I'm wondering how likely she is to be pregnant? Would it make any difference if she doesn't get the injection every 12 weeks, but is always certain to have it one month prior to us having sex, without fail? Thank you.