the problem here it's not the fact that your design looks empty I think you need to change the color palette to have something more harmonious. If all that you need is here why searching to add some new things?
If I can say something more:
- reduce the size of your "cross box"
-replace the "submit" button and finally,
-change the typography for "web project".
Try making the whole form container narrower so there's less space. Keep it all concise and the elements together. This will help UX too. I assume the inputs in the bottom right with the + symbols are for adding languages? If so, there's no clear correlation between the too. Bringing them closer will help, as will adding input labels (it sounds obvious but make everything as easy to understand as possible).