Q: Exported pictures has random resolution

Please restate your question as it currently is not clear

LN

RAW files will always be nearly 5 times the size of a jpeg created from that RAW file.  The only format that you can create from a RAW file during editing that will be close to the size of the RAW file is a TIFF file. 

The resulting jpeg file that you create should be perfictally adequate for all but the most stringent uses. Unless you plan to printing extremely large prints from those files you should not be concerned with additional JPEG compression.  These articles discuss jpeg compressors and image quality:

Does Saving a JPEG Multiple Times Reduce Image Quality

The Real Truth About JPEG images

How Bad is JPEG