I was similar.
Very regular periods around 31 days, decreased to 28 days in my later 40's.
I had a very long, very heavy bleed at just turned 49. Around 3 weeks, small clots, flooding etc. I had transemic acid from the GP and it tailed off and my periods settled down to around every 25 days.
I had another very long, very heavy bleed a few months after my 50th.
Again transmic acid but it wasn't as helpful - the bleeding slowed, stopped for a few days, restarted, stopped etc.
I recall emptying my mooncup before going to pick my son up frlm an explore camp and flooding through my mooncup, pad, pants & jeans into the car seat before I completed the 15 minute journey. I sat on a rug driving home.
I was referred for an ultrasound after about 6 weeks.
Ultrasound showed thickening of the Endometrial lining and I was referred to the gyne clinic.
Gyne clinic did a hysterscopy, identifed a smallish fibroid, took a biopsy and fitted a Mirena coil.
Biopsy confirmed thickening, but no malignancy.
I bleed lightly for the first few months of the Mirena, but once that settled I had no periods (although could still tell I was ovulating, menstrual type symptoms etc for a couple of years, these died down around my 53rd birthday earlier this year).
Definitely get checked out by the GP and don't be fobbed off, this is not normal for you and even if investigations confirm it is just peri symptoms, you should be offered treatment options to help.