|3 weeks is a really long time. You say you have cleaned everything - what have you cleaned them with? Soap and water isn't enough. You need to think about everything that might have contacted the poison ivy, and everything that might have rubbed against those things. Then buy some Tecnu, put some on a washcloth and wipe all those things down very well. For clothing, pour some Techno in with the wash (amount recommended should be on the bottle).
Also, consider other ways you might be gettting urushiol on you again. My pet dog was re-infecting (ok, not really an infection...) my arm where I picked her up, because she was playing in a corner of the yard that had a crop of poison ivy. Had to wash her, and her bed blanket in tecnu.