I liked your story, you remind me that just like you, I have saved several Speedos clothes when I went swimming. Today I also wear my loincloth on quiet days and one day I would like to try it in a pool nwn
I don't remember when exactly it started, but The Jungle Book likely had a part. But the bigger draw for me was Last of the Mohicans, Dances With Wolves and Indian in the Cupboard. That last one was probably even my first actual crush, though I wouldn't admit it until only a couple years ago when I came out as gay. But yeah, ever since I can remember, I've found myself attracted to men in loincloths of all types, but breechclouts especially.
As for creating my own, I haven't really had the confidence to try it. But I have bought some pre-made ones. I have a wool breechclout I wear for reenacting that I think I posted a while back, but I wear it with a lot of other gear as well. I'm not confident enough in my physical shape to go shirtless! Maybe one day... I do look forward to being able to kit up again though.
I am very glad that you discovered your sexual orientation at the same time because of your liking for men in loincloths. Just like you, the same happened to me, only with me it was for the movie "The Jungle Book of 1994" and having my "first crush." I hope one day you will be encouraged to go out without a shirt and have confidence in yourself ;)