Its been 11 days since i was in contact with someone who had covid. i had no symptoms in my 10 day isolation and i am fully vaccinated. is there a chance i will start showing symptoms this late ?

The chance is almost zero because the incubation period (time from contact to first symptom) is less than 10 days.

While symptoms are no longer likely past 10 days, testing would still be recommended in order to ensure you did not have an asymptomatic form still being able to pass it to others. It has to do ultimately with local activity, strain type in the community and following local and work related regulations would be best.