The court shall dismiss the delinquency petition or the violation of probation petition if the child has not attained competency within: 18 months after the date of the finding of incompetency if the child is alleged to have: Except as provided in item (2) of this section, committed an act that would be a felony if committed by an adult; or Committed an act in violation of § 5–133, § 5–134, § 5–138, or § 5–203 of the Public Safety Article or § 4–203, § 4–204, or § 4–205 of the Criminal Law Article; or 6 months after the date of the finding of incompetency if the child is alleged to have: Committed an act other than an act specified in item (1)(ii) of this section that would be a misdemeanor if committed by an adult; or Committed an act that would be a felony if committed by an adult over which the District Court has exclusive original jurisdiction under Title 4, Subtitle 3 of this article.