Hi dear
Virtual hugs to you. A m/c is such an emotionally and physically hard burden to bear. There's no answers to your "whys". I listen to Joel Osteen's Podcasts on Spotify and he said once that we need to have a box in my mind where we put in the "why" questions. Only God has the answers to all the whys in the world and one day on the other side of eternity, we will be able to understand.
Anyway, I can't advise you much about the ultrasound.I was much further along in my pregnancy when I miscarried and the doctors wanted me to give birth naturally but once I was done, they wheeled me into the operation theatre immediately cos they didn't want to waste any time to do a D&C. The midwife explained that it was time sensitive to do the D&C quickly because the cervix would still be open and it's easier to do the D&C then.
I would suggest doing an ultrasound as soon as you can, to ensure that it's all cleared out. You don't need to watch the screen if you don't want to. I hope this information helps you to make the decisions you need in the upcoming days.
Huge hugs. This is such a hard experience I wouldn't wish on my enemies.