How much blood is too much?

Larisa
I have always had a very irregular period, and even when on birth control it was very light and short. 3-4 days and never needed more than a regular tampon every 4-8 hours. 
We are trying to conceive our second child and I was given progesterone to induce a period. I have never bled so much in my life. 
I am going through a super tampon ever 1-1.5 hours. I have never purchased super plus tampons and I did yesterday, they last about 2 hours.
How much is too much? 
At what point should I go back to the doctor and have a check up about it. 
Can anything even be done?