Ovulation Date Issue

Hello all! I've got a question about charting my date of ovulation. I've been charting for 8 mo and now TTC for 2mo. I'm using fertilityfriend.com to chart and the last couple months my ovulation date has been wacky. Last month it said I didn't ovulate though I had clear ovulation pains and a slight temp shift on the 14th day of my cycle and this month is says that I ovulated on day 16 even though I had clear and strong ovulation pains on the 14th. Since I'm TTC now it's extra important for me to get my timing right. Can a person have ovulation pains but not have a temp shift for a few days?

Here's a copy of my chart for this month so far. Any thoughts?
Also I don't know if it matters but I've been having cramping since morning but maybe I slept wrong or something...