i did too! i had real bad cramping which i thought i was o'ing again, and two days later i kept feeling sick! so i knew i was utd but waited until 11-12dpo to test and got a bfp! doctors took blood at about 19 dpo which hcg levels shot up to 760! which was a huge suprise as i never had high hcg readings so early!
good luck hun, i really hope their is a bfp for you very shortly! xxx