It's definitely backlit but I think the edges need more definition. Maybe position the light lower behind their back to avoid the hair becoming blown out. A tiny amount of fill light would give us some detail without losing the silhouette effect. A good test is to view your image very small. Look at it at 5% size or as a thumbnail and ask, "can I still tell what's going on here?" This shot has great potential with a few tweaks, keep at it!