1 week late...

My period is officially 8 days late and I've taken 3 negative tests. I had a miscarriage and d and c in September. It took a till January for things to get more regular...maybe only 1 day later than predicated. When I was pregnant the first time I got a positive pregnancy test the first day of my missed period. My Dr said to wait two weeks after my missed period. Has this happend to anyone else. Does it sometime take a while to get you bfp?? I really don't want to get my hope up too much...but I'm praying I'm pregnant!