Welcome to CDH.
Others have offered some excellent suggestions. If you’re planning a visit with your sister soon call her and let her know you have something to tell her. Since she pierced your ears and dressed you up when younger she likely knows you enjoyed the transformation. When you visit and talk in person let her know how much you enjoyed being sisters. If she isn’t receptive then better to visit in brother mode. She may have enjoyed having a younger sister so she’ll let know know it’s ok.