My stomach looks bigger, but it could just be gaining weight?

Okay, so I'm 16 and in December I went down to Mexico with my family. On December 31 / new years I went to my friends house. She left to her grandmas house with her mom and sister. I didn't want to go so she told me I could stay with her cousin in her house so I stayed. I ended up drinking with him. It was just me and him but we were outside. I got so faded I blacked out. I don't remember sh*t, I woke up inside laying on a bed, but I was fully clothed, I wasnt under a blanket, the bed was made still and it looked like I was sitting and just laid to the side for a bit. When I woke up he wasnt in the room, his cousin was. The girl and her mom were just watching me when I woke up. I didn't think much of it and they took me home. I got home, drunk out of my mind and went to sleep. I woke.up the next day with a headache and I puked. I felt like I was going to puke all day, but only puked after I took a shower. I know I kissed him, but it was a peck . I didn't makeout with him, atleast from what I remember I didn't. My friend kept asking me what happened, and what I did with the guy but I kept saying nothing, because from what I know nothing happened. But then he said ' well if he tried kissing you when you were sober, and you didn't let him, imagine what he did when you were completely drunk ' that's what got me thinking something did happen. Its been almost a month and I'm suppose to get my period like next week. But I'm kinda scared. My stomach looks bigger, but I could just be gaining weight. I'm also burping alot but haven't had any sickness or anything. Could I be pregnant? Or is there any symptoms I should be feeling by now? before this night that I could possibly have had sex with someone, I was a virgin. I've never had sex so wouldn't I remember doing it with him, even if I was drunk since he would be my first?