Leash pulling, not listening

Those who have dogs older than a year - help! My 8 month old dog for the last couple of weeks is pulling incessantly. When he does, I stop walking, say “on me” or “back” or sometimes I just stop walking and he turns and heels. But the pulling is getting worse. That and today while playing fetch he ran for a dog, crossed the street and ignored my commands. Luckily it was 7am and slow, the other dog owner was cool. Is this a phase? What can I do to course correct that will help? Pic of the teen.