I started birth control exactly two weeks ago. On the sixth day of my first week of pills, my boyfriend and I had sex but didn't use a condom. He ejaculated inside of me, which he normally doesn't do when we don't use a condom. I pulled away immediately, but obviously the withdrawal was not effective in preventing his semen from entering my body.

Since last Wednesday (midway through my second week on the Pill; five days after the unprotected sex), I've been experiencing cramps much like those I get before and during my period. A doctor administered a pregnancy test that resulted in a negative; if I really am pregnant, though, I think the test was administered far too early to show.

So I suppose my question is this: how likely does it seem that I could be pregnant? I alternate between thinking I am not and thinking I am. I spend every spare second worrying about what is going on in my body, imagining that every twinge of pain might be the signal that a human being is being created inside me. I know all I can do is wait and take more pregnancy tests in the future, but the waiting is killing me. I'm literally queasy with worry most days.

I'm planning to begin a Ph.D. program next fall, and a baby would seriously derail every plan I have for research and schooling over the next five or six years. I'm worrying myself sick and don't know what to do.