Misdiagnosed Blighted Ovum at 10 weeks?

Hi Everyone. I will try to make it short, but could really use some advice. I am 27 years old, perfectly healthy, no health problems, no problems conceiving and I already have a 2 year old son who was born via c-section. I found out just before Christmas I was pregnant. I have always had really irregular periods, so I am unsure of an actual ovulation date. I went in last week to the doctor thinking I am about 10-11 weeks along. Head for the ultrasound and no heartbeat. We went for the transvaginal and the doctor saw 2 sacs. One was a bit larger than the other. One looked empty, the other may have had something in it, they were unsure. Did a blood test that day HCG levels were at 8,600. Went back 3 days later and they are down to 5,400. I tried to get out of the nurse what size the sacs measured, but there was nothing in my charts. My doctor told me I have two options- a d&c or naturally wait it out. He encouraged me to wait it out naturally and that is what I am doing. I still have no spotting or cramping. Could this be misdiagnosed? I am not sure if I have a tilted uterus or not but I have always had irregular periods and at least 1 UTI every year. When I was pregnant with my son, I had a lot of bladder infections. I don't want to give up hope, but I also don't want to be in denial. I want to do whats best for any potential baby and for myself. I am living an almost out of body experience. Could it just be one sac I am miscarrying and that is why my levels are dropping? Thanks for your help....I really need some comfort and advice!