Not at all, as long as he skirt reaches a bit above the knee and has some volume to it, the skirt should look fine. My Sera Myu skirt is longer than intended, but it still looks fine
Wear some spanks underneath (same colour as skirt) as well to ease your worry!
Sera Myu Eternal Sailor Moon - Sera Myu Musicals - 95%
Mew Berry (Café version) - Tokyo Mew Mew Á la Mode
Usagi Tsukino (School Uniform) - Sailor Moon
Sailor Cosmos - Sailor Moon Sailor Stars
Bubbles - Powerpuff Girls Z