Tetanus injection give protection from wounds that are about to occur in future from contaminated surfaces liked rusted metal or soiled surface. If you take one now it will protect your future wound and one you jave taken in 2019, will give some protection now. After reading your short history, I would say if the knief is old dirty rusted unused one then take one dose of tetanus toxoid, if the knief is your regular kitchen knief that you use everyday and is being cleaned then you don't need any injection, just put one waterproof handiplast and don't let the wound come in contact with water for next 2-3 days. Your swelling will be gone by then.
Next Steps
Buy one waterproof handiplast and put firmly one the finger where the cut is there but not too tightly or too lose.
Health Tips
Don't let the cut area come in contact with water for next 2-3 days. Don't put the handiplast too tight or too lose. Putting it too tight with restrict blood circulation in that part and putting it too lose with let water get into it. through the space between finger and edge of handiplast.