28 day cycle

In march, my cycle ended up being 28 days. But after i input a couple days if spotting right before my ovulation day (i think), glow changed my expected period to just 22 days after the last one. Is a 9 day luteal phase to short.?? Or is glow probably wrong in changing the information.? Help please. Btw, i believe my LH surge was on cycle day 12.