Period question

I don't mean to start a 'pissing contest' over this but I genuinely don't know if I should be concerned.

I usually use a mooncup paired with absorbent menstrual underwear. Today I couldn't find my mooncup and soaked through my menstrual underwear by lunch time. Then I changed into a night-time sized sanitary towel (that is, the largest size) and soaked that in three to four hours - to the point that it was squelchy and heavy and past the amount of grossness I could really tolerate. I get periods this heavy for up to two consecutive days, with a day's lead-up and three days' cool-down (I give it four though, just to save my underwear as the final brownish discharge passes.).

Is this a normal amount of bleeding? Every month I wonder, 'how can such a small organ even hold so much fluid? Isn't it supposed to just be the lining of the wall that sheds? If I'd been told I was shedding my entire uterus, I might almost have been fooled.' The uterus during menstruation is supposed to be the size and shape of a pear.

I know that most guidelines say you have an issue if you get clots larger in size than a medium-sized coin, or if you need need to change your pad every hour. But I just get lots of little tiny clots, and I'm assuming that the 1-pad-per-hour thing is for people who use normal-sized pads... right?

Can anyone weigh in? It's super hard to get a doctor's appointment and I'm not going to waste my doctor's time or mine if this actually turns out to be normal. We need to be able to talk about periods.