My heart goes out to you I have been in exactly the same situation as you. I don't think anyone who hasn't had a miscarriage can quite understand how it can ruin the early days of subsequent pregnancies.
I did the same as you the second pregnancy, early scan which helped for a small amount of time, looking at the statistics from the miscarriage association really helped me. The heartbeat at this stage is such a promising sign.
I went on to have two healthy babies (the first took over two years to conceive after the miscarriage) and both pregnancies I felt just as anxious in the early days. Each milestone did help it ease off though, the 12 week scan, first movements, the 20 week scan etc. Don't beat yourself up for feeling anxious, it's perfectly understandable. High levels of anxiety will only cause harm in the third trimester and by then you will likely feel very differently.
Another way that I got through it was so imagine how I would cope well and what I would do l if I did have another Miscarriage - bit hard to do in current times but I would think oh well I can drink at the next social event I had planned, or book myself a spa day etc with friends. Just something I wouldn't have been able to do pregnant.
Also someone who I knew from work who had some terribly late miscarriages and went on to have children spoke to me at the time I had my
Miscarriage and it makes sense to me now. She told me that when you finally get your baby, you realise that this was the baby you were always meant to have and you wouldn't want a different baby as yours is the love of your life and perfect in every way. I understand what she meant now.
Let those close to you know you are struggling and best of luck I hope this one sticks.