It is entirely possible she sees your mom as "mom" too. She can love both of you just as easily as love you. I don't think they can only love one person. My Yorkie loves my family, yes he is mostly mine and loves me most, but he sure does love my daughter a lot and I am okay with that.
She might just have so much fun with your mom that she loves to see her. I would try to make sure you take time each day to spend with her just having fun. I set aside time where I play with my dogs usually once in the morning and then later in the evening before bed we play again. It helps us keep connected. Give that a try and see if it helps.
__________________  It's raining Yorkies here! LOL Teek  ,Rowan  , Raksha (Grand Puppy)  , Raelyn  |