Positive OPK but no BBT spike

Stef
Last cycle I saw a very clear rise in bbt the day after my LH surge. It was my first time charting. This time I got a positive opk on cd 14 as usual but no clear spike. My chart is a little all over the place this time too. Can anyone help me? I'm on cd 16 now. Could it be that I didn't actually ovulate?