I have been bleeding for 11 almost 12 days. spotting first 4 now heavy bleeding sometimes. not like period. help! pregnancy or miscarriage? or none?

You are describing an abnormal uterine bleeding in a premenopausal woman. There are many reasons for this but the first test to be done is a pregnancy test (pregnancy/miscarriage is a common cause). Other possible explanations for age 18 are anovulatory cycles, medications, thyroid issues, other hormonal problems, PCOS etc. Next step is to see a physician and have further evaluation done.