Fourth c-section and scared!

I am 18 week pregnant with my fourth child. All of my previous children were born via c-section. The first due to a birth defect and the second being 10 lbs. My doctor won't allow me to try VBAC because of concerns of a ruptured uterus. My third c-section was difficult because of the amount of scar tissue I had, so it's making me very scared for this one. Has anyone had this many c-sections? Any advise would be appreciated! Thanks!!