How much blood should you lose during a period?!

I have read that 35-60ml is usual, 44ml absolute average, and anything above 80ml is considered heavy (menorrhagia). This is per period, not per day. I think this was via research where volunteers saved up their sanitary protection and scientists then extracted the fluid from them to come up with the figures (TMI maybe...but useful to know these figures are not plucked out of the sky).
I was in the same position as you, didn't realise until I used a mooncup that I had a problem - I have lost 60ml in a night before. It is hard to know what "normal" is when it is hard to measure amounts and you don't have anything to compare against, so you tend to assume you are "normal".
I would go to your GP and tell him or her what you have found. They should be testing for iron levels - haemaglobin and ferritin as losing too much blood during a period makes you a prime candidate for iron deficiency.
The GP may also suggest the contraceptive pill, IUS (Mirena) or other medications which will lighten things for you, although these are no good if you want to get pregnant at the moment.
I hope you get things sorted out.

If you feel fine then you're probably fine, but talk to your gyno if you want some reassurance. Also, consider that some of that volume is mucous and clotted tissue, and not just all blood. And some women do report that cups shorten their period, so if you're a new user you may find that your period doesn't last as long, or that your heavy days come sooner and your light days are lighter. If you feel totally fine and aren't too worried, I might wait a few months, to see what your average is with a cup, before you decide if there's something to ask a doc about. But if you're really worried or have any symptoms of anemia or anything, I'd go ahead and ask sooner.

hmmm i think thats right