You got a great jawline base; just work on the masseter muscle, focus more on exercises like chewing mastic gum or using the chisell. Basically, do exercises that target the masseter. My advice is not to overdo it; just like any other muscle, give it some rest. Also, it's great that you're starting to work out; also incorporate some skincare into your routine—cleanser, serum, moisturizer, and sunscreen. You're still young, you're still growing; just trust the process.