scared

Any help advice opinions, everything is welcome. Completely lost and confused. Trying so hard to stay postive but BLaH!!
I've had two periods after having my daughter and they were 42 days apart.. not a normal 28 day cycle. 
Assuming I had a longer cycle, and paying attention to the fact I spotted Jan 16th I am about 4 weeks 5 days ish pregnant. I think. 
I was told to go to the ER yesterday because I'm having cramping/pressure and bleeding. Mostly dark red. 
Doctor said cervix is closed. Ultrasound showed a sac and that I'm measuring 4 weeks. My HCG did go up from the day before. 
He said possible three things.
1. I'm earlier than I expected I was (ob went off a normal 28 day cycle putting me 7 weeks)
2. Early miscarriage 
3. Tubular pregnancy (least likely) 
Follow up bloodwork Sunday... tomorrow!
Anyone ever deal with anything like this? I'm trying so hard to keep my hopes high!