My little yorkie, "Sidda" won't potty train!?

Sidda is just over 3 yrs old and we for the life of us, cannot get her to consistantly "go" outside. I work from home so I let her out every 1 1/2 hrs...sometime she goes, sometimes she doesn't. It could be beautiful, rainy, or snowy and it depends on if "she" feels like going. She'll stay out for 20-30 min. running around chasing birds and then come right in and go on the carpet! I am starting to resent her a bit. My carpet smells and I have tried the potty pads...no good. I have tried treats...no good. I tried a cage..no good, altough someone told me the cage might be a little big for her (She went in there too!) I've checked with the vet and their are not problems there, I have no clue what to do and I am considering selling her but we have grown to love her but now, like I said, we are resenting her and not paying as much attention to her because we're mad at her. Please help! Thanks