Oh well, a good amount of lore drops on the same chapter. As reference, on Japan the people starts the second year of high school when they are 16, so the fugly hag dropped school when she was still 16 or at most she was 17, then she gave birth right off the bat, so she may have gave birth when she was 17 or 18, now her son is pretty close to be 20 years old, so at most I think she is 38, so it seems the age estimate done by Daichi coworker at the convenience store was right on the mark.
Also, having on mind sensei was married, then I wonder if the picture frame seen on one of the past chapters was a frame with a picture of her ex-husband.
And yup, they were close to kissing, but Daichi "wish" cockblocked them, lmao.