Statistics are evil beasts and can completely do your head in. But to answer your question, no, I don't think you are kidding yourself. As someone else said, I think a 25% chance is actually pretty good in the whole scheme of things.

I have met women in their 40s who were completely pollyanna about the whole baby thing (single but cheerily saying that if the right person came along then they'd like a baby with absolutely no sense of urgency). I think they would do well to have a look at some stats and get a wriggle on.

In terms of positive stories - a friend of mine had a healthy baby at 44. I had a healthy baby at 41 and after convincing myself that there'd be something wrong at the 12 week scan, the stats actually came out phenomenally well. I know how scary they can be, I freaked myself out too.

Good luck!