You haven't failed her. And her kindergarten teachers will probably be pleased that she doesn't know these things. After all, that is part of what they will teach her. Furthermore, you put your finger on one of the reasons: you did not have as much time to spend with her as you did with your son. We second children never get as much time as our older sisters and brothers! Find opportunities to do special things with her without her bright older brother. Read to her; make special pilgrimages to the library and let her choose the books she wants; talk to her while you do your housework; involve her in cooking activities and talk about the measures. Such everyday things as these will give her better preparation for kindergarten than will special efforts to teach her numbers and letters.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.