Ladies I need your help

Can you all please name everything that causes white discharge. I've been having this white discharge for 2yrs now and it slightly itches sometimes and it burns sometimes when I have sex for a long time. I've been to 3 different doctors. They all checked me for stds and they came back negative. I also was checked for yeast infection and it came back negative. But my doctor gave me the pills just to see if it'll help get rid of it. And I just finished the bottle 3 Days ago and I STILL have this dang white discharge. I know its not a normal discharge cause it shouldn't itch or burn when I have sex. So please if you know anything else that could cause white discharge please let me know so I can tell my doctor what else to check for. I'm going back to him next week. I just really want to get rid of this discharge cause 1 its annoying and 2 I think it is stopping me from conceiving cause I'm constantly having it none stop and its thick and feels like lotion and drys up like glue..

Please help!