Brief background:
Some years ago, I was in a bad way emotionally. I fell into a party lifestyle of late nights, drinking and sleeping around. I had lost my family and was incredibly lonely. All I really wanted was someone to hold my hand at night while I slept. But the only way I could find that was with a series of one-night stands :(
One night I went out and met a particularly gorgeous bloke. He came back to mine, we had sex. He stayed for ages the next day, only leaving because I had to go out as I'd arranged to meet friends. He asked for my number, I gave him my business card 
I never heard from him again.
A few weeks later I found out I was pregnant. My DC is now a teenager, and knows only their dad has never been in the picture.
Only my oldest and closest friends know about this. I was talking to one of them today about various things, and I mentioned DC's dad. My friend asked did I not think I should have tried to find him at some point since I found out I was pregnant for DC's sake?
I've always told myself it was for the best we weren't in contact. But now I wonder if I've been wrong all these years? I knew only his first name, occupation, age, and the area of London where he lived. I didn't think it would have been possible, plus this all occurred some years before I or anyone I knew had internet access.