The wp_get_attachment_image() function will work if you actually put your values in the function. Currently, you have $image = wp_get_attachment_image_src( $attachment_id, $size ); but you need to have something like $image = wp_get_attachment_image_src( 39, 'name_of_size' );. Also, your get_field function doesn’t seem correct. I would read more into the documentation about how to use get_field.
