Hi, I Was Wondering If I Was Pregnant Or Having

Hi, I was wondering if I was pregnant or having something else.. My period was actually on the 21st of August 2016 this month but it's late and I was on my period 2 days after. During my first day on my period, it was normal. I have menstrual cramps like I used to and it was quite heavy but not as heavy as it was like ths other normal months I have during my period. So here's why I doubted I was pregnant. 1st, I had an unprotected sex with my boyfriend about a week before.. After like 3-4 days I started to feel nausea, having mood swings and my lower abdominal part feels quite hurt but there were no signs of having tender and sore breast if so it could means that I will going to have my own period. On the first day of my period, it was a normal bleeding but then I noticed there was a brownish discharge and on the 2nd day, I experienced menstrual cramps like I usually did on the normal months but why does I have pink discharge and it was so light? I can feel that my period is going to end in just 2 days ! I usually have a period which it would lasted for 7 days.. I did not take any pregnancy test yet. My boyfriend and I talks about pregnancy but we did not have any plans to have a baby since I'm still studying in college and was just started but I did told him about this and we are both concern right now. Anyway, he said he will be responsibilities if I was pregnant and would accept the baby but as for me I'm not ready yet. We did had have sex 2 months ago and I wasn't pregnant but this year it was quite way more different. So, I hope you can answer my question as I really need answers this time. My parents didn't know because I know they would feel disappointed if I was pregnant which is scared me the most now