The Lyman 50th manual has load data for a 125-grain JHP similar to yours (brand not specified), but they don't list any loads with Trailboss.
You are going to find this with most load data sources. They aren't a complete list of everything that will work with every bullet. What they are is a variety of loads based on what MOST people will want to do with various bullets.
125gr JHP bullets are "premium" compared to lead bullets, and usually used for full power and +p load levels. Trailboss is a "light & fluffy" powder, physically, designed to fill the large volume cases from the black powder era and give BP level speeds doing it.
Its not that there is no TrailBoss load that will work, its just that most people won't be using it with 125gr JHP bullets, so you usually won't see it listed in the published data.
I realize its what you have, and want to be shooting. What you need to be doing is seeking more & different bullets and powders, ones that are more commonly found in the available data.
You can order bullets on line, powder too, some things are more scarce than others, but stuff is out there in variety.
Look into some cast lead bullets (158gr is the classic) and some other powders, many will work, Bullseye W231, AA No.5 for light plinker loads, Unique AA n0.7 (and many others) will do for midrange up to full power .38s.
For many years I've loaded cast 158gr slugs to 850fps with Red Dot powder as my "standard .38" load. Not because Red Dot is better than others, just because it works well enough, and I had a keg of it I needed to use for something....
Another thing, if online doesn't work for you (and when the virus situation allows), TALK to the people where you bought your bullets. Most of the time, shops will be happy to order things they don't have on their shelves, if you tell them, "if you get this, I WILL buy it".
Or they may be willing to order things just for you.
Also, talk to the cowboy action shooters here and other places online, they use a lot of trailboss and might have a load you can use with what you have now.
I did buy one "pound" of Trail Boss some time back, but never got around to using it. Was a bit surprised that the "one pound can" size was 12oz, not 16.
Its made to fill .45 Colt, .44-40, .38-40 size cases. I'm sure there is a usable load for .38 special, I just don't know what it is.
Good Luck, let us know how it goes.