That's all right.

I know that this might sound terrible, but I have never felt sad about it. I never knew him/her, so I could never feel as if something were taken from me. (The baby was so badly deformed from my mother's condition of excessive amniotic fluid that the sex wasn't determined. My mother just always felt blessed to have me, and I came out perfectly healthy.)
In any case, now I'm curious to see if there are any charts out there which show some sort of evidence of multiple ovulation. I don't really think that mine is, since my body wouldn't have had enough time to mature new follicles---and if it were the case of twins, the eggs would be released within 24 hours of one another. I found an article about it on FF saying that you probably couldn't see a twins ovulation on your chart.