is there a chance of pregnancy or just delay in menses

Me and my bf had oral sex thrice and dry humping with clothes on ,the first tym i gave him the bj i left it in between wen he was at pre ejeculation after that he stood in front of me with his penis out i was fully dressed up his precum was on my shirt but than he immediately got into clothes.my period was due 6 days ago but i still din have them.i even got severe ill due to flu and mouth ulcers and was on medication (antibiotics)for almost 3 weeks last month.now is there a chance of pregnancy or just delay in menses is due to stres and prolong illness?plz help me