Blood test said no ?

Codie
Ok lady 20 days late as of today was at hospital for 6 hours last night for pain no bleeding done blood work and ultrasound to rule out an ectopic pregnancy blood said neg and was 2ml and ultrasound couldn't find any pregnancy but was told could still be one and coz still be to small to show was told any kind of bleeding go back to er I'm really confused as to y this is happing I'm always on time and it's always been a 28 day cycle even befor having my 2 children so what I really wanna know is has this happen to anyone befor and do I have any advice for me plz and thank you x