Miscarriage

My last period was on Sep. 6, I was having 34 ish day cycles. I texted positive Sep. 30 & all was going well & I am supposed to be 6wk today. The last three days I was having severe cramps and then spotting turned into heavier dark bleeding. I went to ER yesterday and my HCG was 400 something & they saw nothing on the ultrasound. I’ll be going back tomorrow for them to check levels again. This is probably a miscarriage right? The doctor didn’t talk to me much and was just saying I was probably only 2-3wk.