Well if you pick single and then enter a child it should automatically switch him to Head of Household. Unless because you live with his parents. But that shouldn't matter if you pay rent. Have to ask around.
Here's a FAQ for Head of Household
https://ttlc.intuit.com/community/family/help/do-i-qualify-for-head-of-household/00/25539
Who is a qualifying person for Head of Household
https://ttlc.intuit.com/community/family/help/what-is-a-qualifying-person-for-head-of-household/00/2...
