am i pregnant

Hi all,

i have had sex many a times with my boyfriend and have used emergency contraception pills all the time(may be around 10-15 in 1.5months). i had to get my periods on 17th june but got it on 23rd june, not too heavy or less, but dark brown in colour and pinkish someimes., it was normal but lesser than everytime i have. my menses lasted for 5days and have very slight discharge everyday since then. i still have very slight dark brown discharge and since 4 days i am facing slight back pain(abdominal) and constipation. my stomach feels so heavy and i am too stressed and not able to concentrate on anything. i did not take a pregnancy test till now. please help me if i am pregnant?