I've always put two spaces after a period, but it turns out that's absolutely wrong. If the only writing of mine that you ever read was my blog you wouldn't have noticed my two-space habit, because blogspot.com automatically changes all double spaces to single spaces when one publishes a post. I thought their space deletion was a glitch, but now I realize it was an autocorrection. Dang.
It was shocking to suddenly switch from thinking I was the smart one doing it right to realizing I was the dumb one doing it wrong, but I am now doing my best to adjust and change. Even as I type these sentences, though, my thumbs can't resist their reflexive double-tap after a period. This will be difficult.
PS- Thank you M. Scott Jones for pointing this out to me.