What Is The Likelihood Of Passing A 6mm X 2mm

What is the likelihood of passing a 6mm x 2mm stone that was revealed on a CT scan to be at the UTV junction on left side with moderate hydronephrosis. I've passed five small ones but this one has taken up residence apparently. I'm flooding myself with water and taking Flomax daily...on fifth day now. How long should I give this stone to leave on its own? I have slight twinges occasionally but not often. I did a UA three days ago and it was normal...no blood or signs of infection. I even repeated test to make sure.