A 9-year-old boy is referred to the PMHNP by the school counselor after his parents request help with his behavioral issues. He is in third grade, and although he is doing "fine" academically, he constantly interrupts, fidgets, talks excessively, and gets out of his seat and walks around the classroom. He has friends, but they often get frustrated with him because he talks over them and he wants to play sports nonstop. At home, he can barely stay in his seat to do his homework or eat a meal. He often gets upset with his parents for trying to redirect him to finish his chores or his schoolwork, and they end up sending him to his room. He does show remorse when his behavior is pointed out to him, yet he is unable to inhibit himself. What is the most likely diagnosis?