How heavy is too heavy? Should I be worried?

I've not always had heavy periods. Two-ish years ago they randomly got so heavy that I'd bleed through an S+ in less than an hour—it was so bad that I'd just stay home from school because it was embarrassing and frightening, and every month I'd end up nearly passing out in class from the cramps. I saw the nurse who recommended me to a doctor in town, who quite literally said "It's probably just fibroids :)" and sent me home with no advice and nothing to help.

I've just dealt with it and sometimes I'll have lighter periods, and they aren't usually long (5 days maybe?), but over the last 6 months or so they've gotten frighteningly heavy again—some days I'm stuck passing blood clots for 20-30 minutes.

Should I try to see a different doctor? I've been really hesitant to see one and bring it up again after being brushed off, and by a woman doctor no less, but I've been getting increasingly worried about this.