It is terrific that she is able to play by herself! And though I understand that it could be hurtful and/or disappointing when she doesn't want to play with you, please do not take it too much to heart. The world around her is new and exciting, and she may just be getting caught up in the wonder of it all!
Perhaps you could set aside a specific time each day that is just for you and her to play/learn together. She may not respond from the start, but soon she will come to expect this playtime with mommy as part of her routine.
Also, make it a point even when she is not directly playing with you to talk with her and explain things to her. Though this obviously cannot happen all the time, it may help her feel as though she is taking part in your activities and let her know that you are still aware of her.
With my son, I often would find a well-loved toy or book that he wasn't playing with and make a big production over my playing with it. That usually got his attention right away! Sometimes he would play with me, and other times he just got the item and played with it on his own.
So just keep going and keep trying new things! One of them will click eventually! Good luck!
(Not to cast a shadow on everything, but if her solitary behavior continues to the point of atypical, such as shunning almost everyone and not wanting to play with anyone else, you might want to talk to your pediatrician regarding social behavior.)