Little help with ovulation calculation??

Ok ladies, so my last period was December 21st, and I have a 28 day cycle...what days would I have ovulated??? Any help is appreciated! I think I'm trying to think and figure all this out so much and so hard that I have officially confused myself   ...my menstrual calendar says I am suppose to get AF by January 18 but of course I'm hoping for a missed period!!! Thanks 

ovulate days 13-15 of a 28 day cycle so about the 3rd-5th?

you are most likely to ovulate 2 weeks after the first day of your last period