How heavy is too heavy?

Growing up I never had any issues with periods, not even now, I’m 27. However recently I started to wonder why they are always so heavy. I mean I’m almost embarrassed buying ultra tampons at the store, especially if I have a friend there with me. And I have to change them every 3 hours. Sometimes at night I’ll even use a pad with tampon in case if it leaks through. I mean is it normal? It’s not extremely painful. The only day I take painkillers is the first. Then I don’t feel a thing. They are always regular, maybe a day off, always 5 days long. Never skipped one. But why so heavy though🤔