If you have been recommended extracting your wisdom tooth because it doesn't have the requires space for its accomodation. Wisdom teeth that are impacted can pose various problems like pain, infection, grow in an aberrant angulations, damage adjacent teeth, become carious etc.
If you prefer to avoid extraction though, you could consider seeking a second opinion from your/ another dentist/oral surgeon and inform them of your wish. You couls also call House of Dentistry by Dr Meenu Dhiman for an online consultation. If there's a possibilty of letting go off extraction, I am sure you'll be told about it.
By looking at your OPG (X-ray), i can tell you that your problem is majorly related to gums surrounding your tooth (Pericoronitis), most probably. I don't think it's carious. Secondly, you have mentioned that you are currently symptom free. I feel you can rather take guidance on how to keep the area clean and healthy.
Next Steps
It's important to consider the professional advice but as you said you are symptomfree, please wait and watch. May be you'll be able to avoid extraction!
Health Tips
do warm saline rinses thrice daily fro a week.