What Can Cause Irregular Periods ,dizziness And Numbness?

Hi for a while I have had a number symptoms and my doctor just dismisses them when I try to get an answer. I am 20. I have always had irregular periods they used to come every 3 months and last 5-7 months, lately they can be anything between every 3-5 months and I will be on for 2-3 days really heavy then stop for up to 2 days with slight spotting then come back on heavily for 3-4 days. I am always extremely tired, I can get 12 hours sleep and be exhausted after a few hours. I get dizzy and blank spells ( I kind of feel numb like I'm not there and I can't remember what I'm doing) I get blurry/ double vision. I get cold really easy even when its warm. I am always thirsty and wee loads because I drink so much. I get really dry skin especially on my feet which no matter what I do never seems to go. I generally feel rubbish all the time. I don't know if they are linked at all.