pregnant??

Me and my boyfriend had sex (my first time ever) about a month ago and I ended up taking plan B and I got my period around the 20th of last month after taking it and everything seemed fine. Though when we had sex this past weekend we did it a lot but we did use a condom every time but since then I've felt weird in my stomach (stress maybe?) and have had more discharge than usual and have just altogether felt weird (once again maybe stress) I'm so worried about being pregnant, has anyone had similar experiences with having sex their first few times or is it just me?