My baby is 9 1/2 weeks. She is getting good at holder her head up when I sit her up. She will support her head and look around. But during tummy time she doesn't really try and lift her head up. She just just kicks her feet like she is trying to crawl but can't and lays on the side of her head and either tries to eat the blanket or her hand. Is there anything I can do to encourage her to try and lift up her head during tummy time?