Confused. A bit of a long read.

I'm so confused. I was diagnosed with a partial molar pregnancy in April. I had one 0 hcg test before my numbers started going up again. Went to the doctors on Thursday and got blood work done and talked to the doctor about getting it drawn every other day through the weekend and next week we'll talk. She told me to get the blood work done on Saturday and Monday. My doctors office is closed on the weekends so she told me to go to the ER at the hospital they are affiliated with to get the blood drawn then on Monday go to the office to get it drawn. This is where I get confused. I go in today (Saturday) to the ER at 9 am. Wanted to get there early to beat the rush. I checked in. Told them I'm just here to get blood work done per my doctor. Again the drs office and the ER are the same company that uses the same database so the Dr didn't give me a physical copy of my orders. So I'm waiting in the lobby with 4 other groups of people. And I'm thinking its just blood work so I should be in and out. Especially because its not crazy packed. Well 2 hours later they call my name and take me to the back triage in a room. This is where I'm confused. I told the guy that walked me back ' I'm only here for blood work'. He tells me its they put me in a room in case they need to have me on an iv and leaves telling me they will be in shortly. The nurse comes and take my blood then the resident comes and gets down my info and listens to my heart and breathing. She leaves then the doctor comes in and tells me they are waiting for my hcg results and may wanna do an ultrasound. Told her I had an ultrasound done at my drs on Thursday and that was just there for blood work so I didn't understand why I had see a doctor. She said depending on how your levels are rising we need to know if it a pregnancy or the partial mole returning. I told her ok but I'm thinking 'my dr and I are in the process of figuring that out. That's why she's monitoring my blood work.' Ended up getting the ultrasound done and being discharged at 3pm. I'm still so confused as to why I had to do all of that when I just needed blood work. I felt so bad because someone could have definitely needed that bed more then me. Is that weird to anybody else or is that just how it is in emergency? I just want to emphasize one more time that my DOCTOR had me go there for the blood work before someone say 'the emergency rooms for emergency only'.