Oh--the shoes in the picture are fine! I was just thinking about the skirt and the blouse.
If you want more color you could look for a pretty cotton knit jacket or small sweater in a springy or summery color that you love.

What do you think about including a small memento of your sister in your outfit? Maybe a bit of jewelry or something in her favorite color, or some other little thing so you can bring a thought of her with you for the day?