Chances of being pregnant..

Okay so last month I had protected sex 2 days after my period ended. The condom broke and we stopped straight away! He didn't cum either. 
​My period is now 1-2 days late, should I be concerned!
​I'm 17, been in relationship for 2 and a half years and I'm not ready for a child. Hence using a condom. 
​Anyone else had similar problems?