Diagnosed with flu b on friday afternoon via nasal test but no symptoms. on tamiflu since fri. when can i go by others? is a false positive possible?

Yes, now.: Why did you have the test with no symptoms? There is always a false positive possibility, but it is low. Symptoms generally arise 1-4 days after infection and you remain contagious for seven days starting from day 1. You are probably already in the clear. Not clear if tamiflu (oseltamivir) is indicated in your case, but if it has been prescribed take for five days then stop.