extremely heavy periods, large blood clots, brown discharge and white, clear, sticky mucus

I'm 19 years old and have been having this problem since I started my period 8 years ago. I have extremely heavy periods to the point I leak through a tampon and pad every half an hour and pass blood clots the size of ping pong balls. Some of my periods will be that heavy that blood pours out leaving a large puddle of blood on the floor and all down my legs. My periods were usually regular but over the past 7/8 months I've been experiencing a period every other week. I've tried tranexamic and mefenamic acid (both with no success) and tried two different types of pill (i still bleed through). I've never had an std and I've never been pregnant (yes I have recently had a smear two weeks ago and I haven't been sexually active for 9 months). I am constantly having period pains even when I'm not on and always bloat up. When I'm not on my period I have Brown discharge and there is a lot of thick jelly like mucus there too. Does anyone have any idea Whats going on with me as doctors keep fobbing me off by giving me multiple blood tests and one even tried to fit me with the coil without my permission yesterday! I'm getting extremely worried as Ive had this problem for 8 years now and have never had a normal period. Please do not advise me on going to the doctors as I've been around 15 times now and nothing's been done.