@Indomie89 My method will be very similar to yours. I've had the same feelings as you, however I've decided to down a high dose of aspirn about an hour before I CTB and then down SA immediately before pulling the trigger.
I think you should list exactly what elements of your plan make you nervous, and find ways to mitigate that. For example, if your worried about the placement being off you could possibly incorporate a second gun into the picture, or take a blood thinner before hand.
I was nervous at first, but just by getting my getting my exit plan well thought out, and my affairs in order has calmed me down immensely. I'm at the point where I have enough confidence in my plan, and the statistics that I'm hopeful it will work.
I know many people have lost all hope, but by holding onto the belief that my plan will be successful has made a world of difference for me.