Emergency room

I went to the emergency room yesterday thinking I was having another miscarriage due to a lot of discharge coming out even though it wasn’t bloody or anything I just felt like it was a lot coming out all at one time and they said everything is fine with my son and that’s he’s actually measuring a week and a half ahead I’m supposed to be 15 weeks today and they said yesterday that I’m 16 weeks and 3 days how this happened to anyone else I’m like kinda confused on how and everything