Congratulations to your sister on her upcoming wedding!! She is sure to be so happy to have a sibling who can write such a wonderful piece of music for her. Above all, the fact that she asked you herself truly shows the deep trust between you two. This piece is lovely, and I can really feel how much thought and care went into creating it. Also, regarding the A-flat around 1:28, hearing that note appear within the overall diatonic harmony, and then watching it resolve, felt like it was telling a story. It was memorable. I think it’s wonderful how it emerges without being too jarring, maintaining the calm and gentle atmosphere of the piece. As for the length, I personally feel that this shortness has its own story, fitting beautifully for a wedding. Sometimes, a length where you feel inspired to add more, and the listeners wish they could hear just a little bit more, is right. Of course, that is just my personal opinion. It really is a beautiful piece of music. Best, Lithl.