Missed Period&Negative Test/ When am I fertile?

Krystal

Came off the pill right before the month started . Missed my period & the morning after I was suppose to be done with it .. I took a test and it was negative. I’m now 10 days late & I am concerned that I don’t know when I am fertile and ovulating .. how will I know ?? Don’t even know when to take a test to check for it .