Hi and Welcome to Canreef!
Well from your description it does kind of sound like an LTA,
Macrodactyla doreensis, but when you say it could also be a
H. malu or a Condy ... those are rather completely different species. Got a picture you could share? That might help solidify the ID a bit.
LTA's do get rather large. Well ... frankly, all of the Pacific hosting species can get large if well cared for. So if it's getting big on you, you might be doing something right.
I think BTA's are probably the smallest of the bunch, most of the time they seem to stay at the 6" to 8" size, but then again I have personally seen morphs of that species that are well over 12"-14" in size, so even the small guys can get pretty impressive.
I don't have any experience with LTA other than I've seen and admired them in other people's tanks... but I know several people on this board who do have good experience with the species, so hopefully somebody else can jump in here and fill in the blanks for us. 8)
Once again, Welcome, and cheers.