I am a 17 year old girl. had painful external hemorrhoids for 3 years. but now it has permentally stayed external, painless, for a year and 5 months?

Maybe not hemorrhoid: Are you sure you have just hemorrhoids? Pain +/- pruritis (itching) from the rectum that recurs may also indicate anal fissures, proctitis (due to infection, inflammatory bowel disease, radiation therapy, stercoral ulcers, rectal prolapse, trauma, etc.), prctalgia fugax. Depending on your age, risk factors, current medication (aspirin, nsaid's), circumstances, you will want to get evaluated.