It sounds like you're trying to stay quiet enough so no one else can hear you in other rooms (a legit concern, I understand), but I think that hinders your singing. You're hitting the correct notes and your voice sounds alright, but it can use more power and passion in your voice if that makes sense. Try finding some place to practice singing a little louder and try some vocal warmups (you can look them up) to help strengthen your voice. I think you're doing good so far!