You need to try to relax...that will help. Make sure you have a comfy chair and that you're up high enough that your elbows are parallel to the machine. Find some clean gardening or quilting gloves to help you manage the sandwich.
Practice more on that scrap sandwich until you find YOUR perfect speed for how fast you'll be moving. Once you find that you'll do better. I promise.
When I read someone struggling I just wish I was closer and could stop by and lend a hand and some encouragement.
You CAN do this.We've all been there. Big hug...