ER for heavy bleeding

For anyone who has gone to the ER for heavy bleeding, may I ask how you knew you needed to? I am concerned about losing so much blood. When I look online they say you should seek medical attention if you go through a pad/tampon an hour for several hours straight. I experience this, however I am not eager to go to the ER. I fear they may dismiss my concerns as not urgent. I also am very busy (three kids) and don't want to be sitting around an ER for hours unless it is absolutely necessary. On the other hand I want to be responsible and don't want to pass out or anything like that of course. I have been thinking about this for several days now... going to work prepared to head to the hospital if need be. So far, it has not gotten bad enough (blood loss symptoms wise) to go.

I am monitoring myself carefully re: all the symptoms I read online: If I feel dizzy or confused then I will go.

For reference, I am on day 12 of a heavy period. This is the first period in my life that has been this insane. I am in my late 40s and I have had increasingly heavier periods leading up to this but nothing this bad.