You are creating a composite image; the lighting seems fine, you’ve got the shadows properly blended in - but something seems off and you can’t seem to figure out what exactly it is.
Creatively combining various images into one picture isn’t exactly easy. Nonetheless, the beauty of composite photography is in its realism and perfection. This article on Fstoppers features a video by Unmesh Dinda of PiXimperfect explaining (step by step) how to check and match colors perfectly when making composites in Photoshop. Using the tips in this tutorial you can create an image that will be almost impossible to pick apart.