As a disabled person and advocate, I'm going to go with a gentle ESH. Normally I'd say NTA because there is absolutely nothing wrong with your choices for your daughter. But the moment that woman started asking personal questions about your daughter's body ("Why doesn't she have legs?") and you consented to engage with her as if it was any of her business, you became a bit of an AH too. Your daughter's body and medical information is no one's business except hers, yours (as long as she is underage), and her doctor's. You are not required to explain it to strangers in a Wal-Mart (or anywhere else) no matter how curious they are, and I can tell you as a member of the disabled community that it's something that many of us carry for YEARS . . . watching our parents talk about and "explain" our bodies and illnesses to complete strangers as if we owe them something. Nosy people are not entitled to answers. Other than acknowledging that she was your child, the only answer that woman needed was, "I'm sorry but I don't see how my child or her body are any of your business, any more than how you choose to walk around is any of ours," and for you to walk away.