Considering you're not sure if it was indeed dog scratch, even if it is, its still a category II wound(based on the info). First and foremost in any exposure case is wound cleaning and vaccination.
Rabies vaccine is very much effective even after 24 hrs of exposure if the schedule is completed. Considering its been 3 months since that and you dont show any symptoms, you're very much safe and risk of rabies is extremely low.
Next Steps
For any future animal bites or scratches, wash the wound immediately with soap and water and seek medical care early.