Hi, my girlfriend had an abortion about 2 months ago, and she hasn't gotten her period yet. She started birth control the day after the abortion, and we started having sex again about 5 days into the birth control. She has taken 3 pregnancy tests between the first and second month after the abortion and all were negative. She spoke with her doctor, and the doctor told her that if she didn't start her period by the end the the second month she might be pregnant, and we have a doctors appointment next week. I'm a little confused, if she were pregnant, wouldn't the pregnancy hormone show up after the first month when she took the pregnancy tests?

Thanks you for your help.