Hi, I Am 34 Year Old Lady. I Was Expecting

hi, I am 34 year old lady. I was expecting my period on the 25 the of Aug 2015. it didnt come. then a few days later I tested positive for pregnancy. i started spotting and bleeding (like normal menstruation) no clots, just before I get into 5 weeks pregnancy and just ruled that maybe the egg had not implanted well. a few day after my 'period' I had serious cramps like i was miscarrying and bled fresh blood like i had a cut and the bleeding lasted a few minutes. I then tested again and the result was still positive for pregnancy. I waited two more weeks, tested again and i still got positive pregnancy. I went for a scan and they said everything was normal, my womb and cervix were clear. I was not pregnant and that my womb measue 8.5cm. Now two weeks after the scan, no period and still have positive preg test result. am now confused. does HCG take that long to go down after miscarrying that early?