Am I pregnant or it is just PMS? Please help me!!!

Patient: Dear doctor, I would like to ask you a question. Last Friday, my boyfriend and I were just messing around on his bed after taking a nap. He took off my shorts and underwear and took off his shorts but he was wearing his underwear. We made out and did a few minutes of dry humping.. And we were pretty sure that his penis was rubbing my vagina instead of the tip of his penis. Throughout the whole session, he did not ejacuate at all but might have some precum which he did not really know or notice. So on Tuesday which was 4 days later, I felt bloated and losing my appetite. My stomach has been gurgling and I have the tendency to burp at night these days. On Wednesday morning I woke up hurriedly because I thought I was late for a school interview but I wasn’t. And my heart was beating so fast I started to feel like vomiting but I didn’t vomit out. As my period has not come yet and I haven’t miss it yet as well because I remember my previous mense came on end of January. And today I saw brown discharge when I wiped my vagina. I’ve read through many researches, forums and still can’t find out if I am pregnant or it’s because my menses is coming? My boyfriend even went to check his underwear and said it was double layered which was quite thick. We are 90% sure no semen went into my vagina but my vagina was really wet at that time.Also, I never really encountered losing of appetite prior to upcoming menses. Maybe I did but I didn’t pay attention to it. But because of the research that I have seen, I kept thinking every symptoms are happening to me. This made me stressed up and scared. Please help me. Thank you so much!