Isn't this why the site tracks which chapters we've viewed and which ones we haven't? So we can find our place even after taking a long break? Just have to make sure you're signed into the actual mangadex site, I would imagine (the forums use a separate login).
Anyway, I agree with one of the others- just restart. That's so close to the start of the story, it's kind of moot, and might as well get better acquainted with the context by reading back several chapters.
Continuing with my 'PSA announcements', Volume 18 (whenever it will come) will change the numbering of these 'no volume' chapters at the end, just as has happened with prior Volumes. The overlap is around 7 chapters. People can double-check this by looking at the last 7 chapters of Volume 17 and comparing them to the first 7 'No Volume' chapters after Volume 17 as of this posting. The content should be repeated. Come Volume 18, the content of this chapter will shift to where it belongs in Volume 18, while the entry for this chapter will shift to whatever will belong in this chapter for Volume 18. The comments will not change, so they will be associated with the wrong chapter content come that time, sadly.
