17 year old girl , unprotected sex

hi, i'm only a 17 year old girl.
i've been taking the birth control pill, but about 3 times in the past 2 months i've had unprotected sex before taking my pill. i had a period the first month, but then the second month, i noticed that when i went to the washroom i had a little bit of blood on my toilet paper, the next day i had more blood, and had to wear a liner cause of it. but by the end of the day when i got home from work, all the blood was gone, and it was jsut brown discharge, which is usually how it is after my periods, and now theres no blood. i've had some pregnancy symptoms as of : nausea, fatigue, loss of appetite, sometimes i feel bloated, have been noticing my nipples are sensitive when my bf plays with them, have felt some weird things in my stomach, and been getting many back pains.
i was just wondering, could i be pregnant? i still havent went for a pregnancy test, but am planning on it soon. probably before i start my next birth control pack. please write back. thx