Some Yorkies are very difficult to potty train. Mine is 6 (YEARS) and stills goes in the house often. Most can be trained but occasionally, after doing everything right, some will still have accidents often.
Ellie is way too important to me to give her up because she pees inside too much. Three-fourths trained is good enough for me.
Why can't you put her in a crate during the day and take her outside when you let her out?
I wouldn't expect too much til 6 months and maybe even a year.
If you are going to rehome though, please, for her sake, do it now before she gets even more attached to you.