Question...??

Leticia
I had my IUD out 9/28 and started my period (maybe) 9/29. And I'm not to sure if it was my period or just bleeding cause they took out my IUD And I check on 10/17 and I was ovulating and I checked 10/13 I was pregnant.  So how do I know how far along I am. Is it from my so called last period date 9/29 and do I start from my ovulation date. Please help.