My son is who is now 4 was always behind about 3 weeks. He walked when he was 15 months. I was so worried that he would not walk and when he did he was on a mission!! He  was so small though that everyone looked at him and said how ild is he? He was a very very small baby. But I also have a son who I have talked about on here who has Fragile X syndrome. He does not have cah. He has had very low muscle tone as well and walked when he was 17  or 18 months old i can not remeber. But he would not do a lot of things either but that had to do with fragile X Syndrome.  I wish you well and before you know it they will be holding their heads up, crawling and then walking and you will think where has the time gone. I wish your baby and you well.

God Bless,