Hi, I Am 21 Years Old, But These Past Week

Hi, I am 21 years old, but these past week I haven't been understanding my body. I have been feeling very tired, back pain, very moody, breast sore and it got bigger.I have been feeling nausea. There some certain scent that makes me want to puke. I am always using the washroom more. The last time I had sex was in July 3. The night I had my period. But it was very short I normally get my period 7 days straight. But my last period I got 5 days but it was heavy for only 3 days and light afterwards. So am just wondering am I pregnant or not? I am suppose to get my period next week and I normally get symptoms that it's approaching but this month no symptoms. Cause my boyfriend believe I am?