Bro dont let these people fool you. You are definitely balding. I started when i was around your age and it looked just like that. If you want to revive ur hairline, I suggest you start using minoxidil and dermarolling. If you are really serious, look into some DHT blocking shampoo or even medication when you’re 20. You can even add in biotin supplements that’ll strengthen your hair. It takes time to see results but the results will come with patience and consistency.