How do I get rid of the mindset of what-ifs?

AB
I really want to try for a VBAC this time but I can't help but feel shaky and not confident enough in my decision. I can't help but think what if something goes wrong? 
 
Plus, the people around seem as hesitatant as ever instead of supporting me which adds to my self-doubt.
How do I change this mentality and become more confident that I can do it?