I had the heavy bleeding at the start which lasted about 2-3wks, this then slowed a little but would go heavy again at times, i bled for 13wks straight after i had DD and the Dr's couldn't find why.
My internal tear was fine, had in internal U/S and nothing.. did a course of AB's and still didn't go... once it did stop i got my AF back 2 wks later and i was still b/f.
If your worried just ask your GP if it's normal.. they said mine was until it kept coming back heavy for 3-4days at a time...

Hope it all goes soon!