To Convert NSF to PST first try a manual process which is described here: cybrary.it/0p3n/convert-nsf-to-pst-format-and-migrate-ibm-lotus-notes-data-to-outlook/
Using this Manual Process I exported my 24 GB NSF data into PST format but I didn't get my complete data, I lost some of the emails in the PST format. Thanks to god I had the backup of my NSF file.
After that, I tried MailsDaddy NSF to PST Converter which converted my all the NSF data without losing a single bit of data and also maintained my folder structure and inline images in the Outlook PST. You can Get more information about the tool from its official website.