Not sure??

So I'm not sure what is going on or if it's normal or not. I usually ovulate on cycle day 11 or 12, for the last 3 months and now I am on cycle day 15 and have been testing for the last five days at the same time every morning and still haven't ovulated. Also last month my period was only 2 1/2 days maybe 3. Not sure if this is normal or not! Any help is greatly appreciated!