MY HCG LEVEL IS HIGH MY U/S DOES NOT MATCH

am about 5-6 weeks pregnant according to my LMP. Yesterday I started bleeding bright red blood and had mild cramping. I went to the ER to make sure I was ok. They did bloodwork, a pelvic exam, and a vaginal and abdominal ultrasound. When they did the pelvic exam the doctor told me my cervix is closed, good. When he did both ultrasounds he could barely see anything in the sac and there was no heartbeat detected. He said i had to be about 3-4 weeks with the results of the ultrasound. When my HCG levels came back, he said he would have liked to see a lot more development in the embryo/fetus (not sure what it is called). My HCG levels are 8797; every site i check says with those levels I am 6-8 weeks. The doctor said my levels do not match the development. He also said there is a chance everything can still work out. I have to go recheck in 48 hours, and see a doctor. Is there any possibility that my levels can just be extremely high at 4 weeks, or am I most likely looking at a miscarriage. I know that I will have my answers soon, but i want to prepare myself for what they might say. My fiance is also very happy and hopeful, we just are wondering if anyone has any insight or suggestions. Thanks.