Images in CKEditor don't retain size
You are looking for Insert module, using this module you can retain the sizes with the help of image cache.


  Insert is a utility that makes inserting images and links to files
  into text areas or WYSIWYGs much easier. It adds a simple
  JavaScript-based button to FileField and ImageField widgets. When used
  with ImageField and ImageCache, images may be inserted into text areas
  with a specific ImageCache preset.





Support for all major WYSIWYG editors, including tinyMCE, CKeditor, the WYSIWYG project (the recommended approach), and plain text areas.
Insert images using ImageCache presets
Maximum width setting for inserted images (for combined use with the Image Resize Filter module)
Per-field insert configuration