I am surprised you washed it. I’ve never heard anyone washing gifts before gifting them. Typically if a person wants to keep a gift, they’d wash it themselves.

After you washed and ironed it, it might not be possible to return. If it wasn’t washed and ironed, I’d return it and just send her a gift card so she can make her own purchase.

Since you already washed and ironed it, I’d either mail to her and let her deal with it or keep it for myself.

I’d not buy clothes for people who are very particular what they buy.