Pregnency related question. Exact issue.

Hi,I am nitu,27 years old,just wanted to know few things about pregnency and wants to check with some symptoms by providing you the symptoms which i am facing now.Actually i had my periods on 20th of january at 4 in the evening and my period was over on 5th day from 20 and till 7th day i had an unprotected   sex and i have counted 7thday till 27th by 4 in the evening which was the safe period according to me,and today its the 16th day from the date my periods started and today just now i noticed brown discharge which was a bit different from the normal one,so could you please tell me that is this a symptom of pregnency and also am having a bit pain in my breast,so i am worried a bit,that is it early symptoms of pregnency or is it normal to have because i have not faced this before ever except of during my periods.so please doctor do have a look on this and please do suggest me the exact issue.