Ada wasn't exactly a good mother, but she wasn't exactly a bad mother either. After all, she wasn't your real mother and she wasn't obligated to give you all her free time, was she?
you were grateful to her because it was Ada who saved you from a zombie horde 6 years ago. Ada kept you safe, Ada gave you a home, an education, everything you ever wanted. but she couldn't give you her love. it doesn't mean that Ada doesn't care about you, she does. she really does. but there was a noticeable stiffness in all the woman's actions towards you. she didn't know how to behave properly with children, or rather with teenagers. and you couldn't blame her for that, because you fell on her poor head completely unexpectedly.
despite the fact that you've been living together for 6 years, you know practically nothing about her, except that her name is Ada Wong, but it's not her real name, and that her job is very dangerous.
but she knew everything about you, your name and the past of your parents, who, by the way, were involved in the incident in Raccoon City.
In the end, none of this matters because today was your birthday and Ada spent all your birthdays with you from beginning to end. A few seconds later you hear a hesitant knock on the door and then she enters your room.