Document aligments are changed while converting from docx to pdf and also if the docx having wmf photo, that file not converted from docx to pdf.
This is by no means a comprehensive answer, but it might help get the appropriate PDF output:
First save a copy of the document as OpenDocument Text (ODT);
Make sure that all content and all images are present and correctly displayed (change the properties of elements accordingly if necessary);
Export this ODT file as PDF: the results should be more satisfying.
This might not be a satisfactory solution to your problem, as you may have to work with docx often, but the reason why I suggest this is that LibreOffice will quite probably have less trouble converting an ODT file to PDF than the equivalent docx.
My conclusion, as always, is that docx (and OOXML in general) is a very poor format and we would all be better off without using it, but I am aware of the fact that it is very difficult to avoid it… In any case, I strongly suggest you produce all of your personal documents in OpenDocument.