Thanks for the query.
If you have not taken any anti tetanus
shots within the last 5 years, you can take a booster dose. It will give you immunity against tetanus. Since you have not got any problems till now, that is even after 3 weeks of the bite, you need not be concerned about rabies
or tetanus infection from the bite.
A vaccinated dog usually is a safe animal with regards to any bite from it. If it did not show any symptoms of rabies within 10 days of the time since it bit a person, it is safe to say that it is not rabies infected. Hope you are relieved of your concern now.
I would suggest you to take a booster dose of tetanus vaccination
if you have not taken it within the last 5 years to protect you from the infection later on.
Hope I have answered your question. Please let me know if any further clarification is required on anything else. Thank you.