I went to the doctor last thursday because I was spotting. The doctor told me that it was likely implantation bleeding and to try not to worry too much. She took hcg levels on thursday and had me repeat them on saturday. I had my first OB and ultrasound appointment on monday. When we went for the ultrasound we could only see an empty sac. The doctor said we might have been too early with the ultrasound. I am sure of last period that was on august 17th. That would have put me at 6 weeks the day of the ultrasound. Is there any way that I was not quite 6 weeks? She also took a new hcg level the day of the ultrasound. I called and the levels had increased from around 6000 to between 9000 to 10000 on monday. They did not double. I read that it takes longer for levels to double once you reach 6000. The doctor is having me come in for an ultrasound on tuesday. She said we would see if the pregnancy was going any where based on the hcg levels and the next ultrasound. Has any one had any thing similar happen to them? Did you go on to hace a healthy pregnancy? Any advice would be greatly appriciated.