That’s something you’ll have to ask your immigration office. They may be willing to accommodate your times, but they may not.
If not then you can apply for a 60 day visit family extension (if you haven’t already done so) to get you to the 19th if needed and then start afresh with a new Non O when you return.
Yes it allows you to enter Thailand within 90 days. On entry you will get a stamp for 90 days (technically 89 further days as your entry date is day 1).