Try this, instead of handing her the toy, take her opposite hand and guide it over her body to the toy. Keep doing this until she gets the hang of it. It may take a while. Try to resist simply handing her the toy, show her how to get it herself. You can also try to jangle toys out of sight, over her head to get her to turn onto her side and look over her shoulder. Also, when she is on her tummy and ready to turn back over, don't pick her up and turn her over. Guide her arm and leg over her body and let her get used to the feeling of being "rolled" over. My DD isn't doing what I thought she'd be doing by this time. I try not to compare, but it's hard sometimes.