What have you done about heavy flow so far?
Not to underestimate the hell you're experiencing, it's just that often doctors are plain bloody useless at helping with problems like this.
My periods are very heavy, to put it into perspective; ultra tampon, overnight pad, and clothing - leaked through all within 15 minutes. In my teens the only option I was given was the pill, which didn't work and caused me to have mini-strokes, it took my own research to find ways of helping. Some ideas that may be helpful to you;
Firstly has your doctor ruled out problems like hormonal imbalance or endometriosis? If so, and everything has checked out okay, have you tried taking tranexamic acid? You take three tablets a day for the first few days of your period and it can lessen your flow and length of your periods.
If open to it you may also want to look into complimentary therapies such as acupuncture or chiropractic care - I've met a few women with heavy flow who have sworn by these treatments, they are pricey as they aren't on the NHS, but they are a real option.
Healthy diet, obviously lots of iron is the most important, but also plenty of magnesium, zinc and calcium for menstrual health, vitamin E to regulate flow, and vitamins A and C to regulate estrogen levels to lessen flow. Seaweed is also known to help as it is a source of iodine, which helps to revitalize the endocrine system, however if not up for eating seaweed then you can just take kelp capsules from health stores.
Get a menstrual cup, for a start this is the best way of managing flow as they hold significantly more than tampons and pads combined and have light suction to prevent leaking. You can feel when the cup is full, and even if you don't empty when it needs to be emptied it's still only light leaking rather than the full flood you get when tampons or pads leak. Menstrual cups can be worn overnight which tampons can't so saves waking up to a blood bath, and for many women cups can even lessen flow. Menstrual cups have been the BEST things to help for me with my heavy periods.
Coffee is a good way to lessen flow as it is a vasoconstrictor so constricts blood vessels in the uterus preventing heavy blood loss, it isn't a huge difference but for me it does help. Look into taking herbal treatments daily throughout your cycle, particularly helpful are; chaste tree (tincture is best - a few drops in water once a day will help), evening primrose oil or black cohosh.