M.L.
It could be that your mother wishes she had been a bigger part of your life before - and now that she sees you with friends and church activities of your own, she feels as if she's lost out for good.
You can't be her little girl any more (except in her heart!), but you can keep inviting her and including her when you can. Keep on being gracious and loving to her as you live your life. She seems to be in the process of sorting things out; you can't do that for her.