It took me a few yrs to become regular, but I ended up on a 45-day cycle, more or less, instead of 28 days. Sometimes the PMS would show up for a 3 wks, and sometimes only 3 days, but it was clearly related it.
If she goes to the dr, s/he'll probably have her take her temp every a.m. when she wakes up, to find out when she's ovulating. She'll have to keep a chart/graph. If she won't even record her periods she won't want to take her temp at 6 a.m. every day and make a chart!
Personally, I don't think 13 is that much to worry about, but it's up to you in reg. to whether you want to make an appointment. It's just that it's so hard for her right now.
Take care.
