my suggestion is that you can see your old account's skin by using minecraft beta 1.3, so the skin must be somewhere, which means you are technically wearing this skin (but only on old versions of minecraft) and I thought there was maybe a way to find people's old skin using an old versions of minecraft.
You can, by doing what I said.
We can't look up player's skin history, we store people's skins into our own history log by saving the skin they were wearing when someone looked up their profile.
Nothing you can do about it really. There have been skin stealers for years, but Name MC just makes it easy to download skins. Look at it from this perspective, other people possibly half way around the world is using your art, something that you created. Think of the millions of other individuals who will see that skin. It's something to be proud of in my opinion.