I always get regular pure discharge which I wash off with my hand while doing istinja. But I forgot to use my hand and just used the hand spray to pour water after urinating. When I got up the wear my underwear a drop of water fell on my clothes. Then I remembered that I didn't wash the discharge. I used the tissue to check and saw there was discharge. Then I felt if the water drop which fell on my underwear has urine on it. But the drop was clear in color so it was not mixed with urine. My body was wet I didn't dry it and put my clothes on and got out off the toilet. My wet body made my clothes wet too. Then I sat on the chair. Then I remembered that I should have smelled it to check there was urine or not. I didn't find the spot later. I have changed my clothes but now I feel like the chair is impure. I thought of applying the rule of certainity but I am not sure if this rule can be applied now since I didn't smelled it to check it was urine or not. Am I having waswasa or is the chair really impure?