Ovulation occurs in mid cycle not at end of cycle.
Yours is a 28 days cycle, so your ovulation must be occuring around day 14th of your cycle.
Stay assured, you can never be
pregnant if you had it on 5th jan.
Next Steps
keep calm and wait for 3rd feb. you will get your periods then. :)
Health Tips
when in doubt, always use a condom.😊