Do any moms have tips on how to get baby to sit on there own? My son just passed the curve where he’s not underweight anymore. He will be 7 months on the 16th. He’s 27 1/2 inches long and is 17 pounds 10oz. He doesn’t know how to sit on his own, he can roll over and when he’s on his tummy he rocks back and forth. He wants to be on the go but doesn’t know how to move his arms. We have the chairs to help him but he leans to one side and cries every time. Suggestions??