I had my period in January. 3 days after the end of my period I had sex for the first time. We used a condom but it tore and I flipped out (even though he didn't ejaculate). completely forgetting that I have the nexplanon implant, I stupidly took plan b ( even though apparently plan b doesn't even work for someone my height and weight of 5'7 and 195). After about a day of headaches and moodiness i felt fine. However a month later my period never came. I took two pregnancy tests a day before my due period, 2 more a week after and 2 more almost 3 weeks after. They all came back a solid negative. However im still scared. Im only 18 years old and I realized quite quickly after that having sex was a mistake and that I wasn't ready. But now I've missed my period 3 times and it doesn't look like it's coming this month either! Before with just the nexplanon my periods came approximately every month- every two months. Has anyone experienced this before? And is it even possible for me to be almost 4 months pregnant and not know it? I mean im tired all the time but that's it... And as a college student that could easily be explained away...