Extremely heavy periods & low in iron

Hi - just looking for any advice from anyone who’s had a similar experience. I have always had a very heavy period that lasts 5-6 days, think overfilling a cup within 3-4 hours. A couple of years ago I had my bloods done and I was low in iron so I took iron tablets for 3 months and the GP said I didn’t need any blood tests redone and to stop taking the iron pills. Fast forward a couple years later with similar periods, I move abroad and everyone here gets routine bloods taken every 6 months so I got mine done and same thing - low in iron. My GP asks about my periods and tells me it’s possible the heavy bleeding is linked to the low iron. So im thinking I must have always been low in iron for the last couple of years? Is there anything else I should ask to get tested for etc?

My periods are regular.