whoooa, thnx a lot Gents for all the comments and help. I do run some mods, I did checked them with Wolfpack345 (form YT). So I run same mod he runs. He did not had any issue so far.
Also I do run Hsie patch which has 4gb included. I also save games on different names all the times and if I want to save under same name - I simply delete the one before instead of overwriting (agree on that saves like to corrupt when You do them over and over at the same file).
In the end I did reload the last save succesfully after rolling back via SH3commander. I really dunno what was the issue. Do I have to do rollback each time before I close the game or whenever I try to boot it up before playing? Or that was lucky catch?
I do my saves on open seas, surfaced, on deck, no radio/sonar/visual contacts, away from land at least 100 km.
Anyhow, hope that won't happen again or if it does - rolling back will save my arse xD
Hope You have a great of a day Champs! Cheers