Possible miscarriage. A possibility?

So I'm not 100% but I'm pretty sure I just had a miscarriage. Some time ago, I had unprotected sex with my partner and he did not pull out. I was on the pill so I thought nothing of it. I was having early pregnancy symptoms last week but I chose to ignore them because I am 19 and was scared. I got my period - or so I thought - on Monday. But there was more blood than usual and it was a brighter red than normal and the viscosity was lighter as well. My cramps were so intense to the point where I couldn't move and they were more central to my front rather than my back or all over like normal. Tuesday I was changing my tampon and there was something on it. It looked kind of like tissue, or a membrane of sorts. So I knew it wasn't a blood clot. I texted my friend and sent her pictures of if. She said that she has miscarried twice before and said that it sounded/looked the exact same and that she estimated I would've been around 3-4 weeks pregnant. Is this a possibility? I still have pics