First and most importantly, congratulations.
I know what you're going through as I experienced a m/c after HB.
I did go on to have a successful pregnancy and you will too.
What got me through was asking the u/s techs at every scan to start with "baby with a hb". I wasn't going to survive them looking and measuring and messing around. I wanted (and got) that reassurance by telling them why I was nervous and having them cut to the chase every time.
My OB also was in on it. If at any point during the pregnancy I felt nervous or had trouble finding the HB on the monitor they told me to come straight into the office. One time I had that scare and walked right in and they let me hear the reassurance I needed.
FF to delivery and my main OB who saw me through my worst was determined to be the one to deliver me. She missed it by an hour but was my first call after my mom.
I know it's hard, so hard to believe and trust again. But I did it. So many others have done it and you will too.
Last and most importantly, congratulations.