Was diagnosed with 3mm uvj w month ago. took two urine test at the er department two days after and both time there was no blood in the urine. does that mean i passed the stone and didnt catch it? havent had pain for other a month?

That stone has likely passed and you have not caught it if you did not use a strainer all the time. However, it may be still in your bladder & it no longer causes hematuria. When stone moves it irritates the ureteral mucosa which results in pain and bleeding. Most small stones are passed out within days or weeks but in some cases, it takes months before the stone is passed.