Very Confused. So I Found Out I Was Pregnant Over

Very confused. So I found out I was pregnant over a week ago. Done a test then next day started bleeding so went to hospital who confirmed I was pregnancy and my hcg levels were 1228 then was told to go back to early pregnancy clinic 48 hours later for another blood test which had dropped to 900 . They still scanned me a couple of days later and nothing there. So said it was def a misscarriage. as not even the lining was thickening it was like no pregnancy at all.

2 days later I got some horrible pains in my stomach so went back to a+e who done another blood test which said has gone up strangly which was 1087 so not a lot but still up. 

so they sent me home and phoned me to to back in today to have another blood test and scan to check for eptopic pregnancy. the bloods they done today come back slightly higher again at roughly 1324 so still not doubling as they should. 
The scan I had today still didn't show anything at all no sac or anything. . He found an egg in my ovary which has said is normal and will just pass itself. he checked the fallopian tubes and nothing there and no baby anywhere at all. 
He is saying it's an unknown pregnancy and that I have 3 options 

1. let it go naturally 
2. have the M injection his choice ideally.
3. operate which he doesn't advice at moment as not in pain. 
I said to him I will like to wait and let it go naturally as at the moment the levels are going up and don't want to just flush anything out. as I told him I am very uncertain on dates and could just be too early to see anything on a scan. 
he has booked me another blood test and another scan for a weeks time to see but he said then it will still be failing and will have to have the injection booked then. 

Could I still be Pregnant? Could it be vanishing twin? Could I have misscarriage or what?
Please advise me as so scared
Thanks