Have a great trip! I like you was very scared for my first time last year. After I went through my first house which was American Horror I knew I would be fine. Like previously mentioned the congo lines worked great for me at the beginning, because you do not get every scare. That helped ease me into it and made me able to focus on the scenery and the totality of it instead of constantly looking at who was going to jump out at me. My friend on the other hand and I am sure a lot of others as well, wanted gaps in the congo line so they could get every scare. By the end of our two days there I would go first and pretend I was brave. Don't get me wrong it is scary, but there is so much going on other than the scares, that makes it awesome and enjoyable.
The scare zones I thought were more amusing than scary. The photo ops in those were great if you are into that, and I thought they were fun.
DA is the same as it is every other time as I remember. Except it was nearly empty the two times I was there. It is great to jump into, to take a break, get drinks, with little to no wait, go on Gringotts, bathroom, and then run right back into HHN.
So once again you will be fine, I tend to be the one that screams in the movie theater during a scary movie, when others remain quiet and while I did scream several times going to the houses I thought that I would be scared 100x more.