How do I know if I'm hemorrhaging?

Depends. If the bleeding is external, you will see a lot of blood! If it is internal, you may not know until you get very sick. Early signs may be thirst, dizziness, weakness and a rapid pulse. Why do you think you are hemorrhaging? If you feel that bad, you need to get seen now! With vaginal bleeding, if you soak a large napkin completely every hour, then that is a worrying sign and get seen.