In your Forms process, go to your save to repository task and check the configuration there. Which form is being saved? Open up that form and look at the layout in the designer, are the fields small like shown above? Or does the designer show them bigger.
It's possible the form you are saving to the repository is different than the one being filled out, and you just have to make the fields wider in the form that you are saving.
It's also possible that the layout designer shows the fields as very small, but CSS was used to make them bigger when filling out the form. If so, that CSS may not also apply when generating the PDF of the form. One way to address this would be to open up the fields and make them wider from the layout designer instead of using CSS.