What do I do?

Me and my partner had unprotected sex on the 25th of November and this was the day or day after I was ovulating the most I have been getting my periods every 28 days for several months now as they have finally regulated themselves and my period was due between 3-5 days ago but no sign of it yet I just keep getting slight cramping in my lower stomach. Could I be pregnant or would it be too soon to tell?