Miscarriage???

I had my period about 4 weeks ago. At the end of it me and my boyfriend had sex (unprotected) and a few days later we broke up. 2 weeks after my last period, my period started again, its been bleeding very heavily, can only have a tampon in for 20 minutes till it bleeds out, pads last 1-2 hours. I looked up info and i believe im having a really premature miscarriage and didn't know i was pregnant. I believe i might have ruined what could have been by drinking a week before this bleeding started. Im on my 12 day of bleeding. Online said if it goes over 14 days to go in to finish out the miscarriage. (If thats what this is) should i think anything of this? As in either miscarriage or heavy period change? Should i go in now?