Hi and welcome to YT
. I feel your pain, I truly do...many of us do.
Personally, I think the whole "they won't soil their den" thing is a fallacy...only bc I've just never seen that to be true in my own experience, ya know? I mean, puppies go when they have to go, wherever they are at the time.
Do you use rewards/treats when she goes outside...? Have you tried placing a potty pad outside (put some of her potty ON the pad so the smell is there), if she is familiar w/ them, that is...?
There is a good training guide
here....if you want to see if it has any info that you don't already have, PM me with your email addy and I will send it over to you immediately.