My mother and one of her sisters had all c-sections (8 for mom, 6 for her sister). Her other sister had a vaginal birth. My sister and I both had uncomplicated vaginal births. We were both worried about it too, especially since my sister is built a lot like my mom, but, though her labour was harder than mine (I'm bigger than she is) she was fine!
You can do it! I think that good support has a lot to do with it in many cases! (not all of course - there are some women for whom it just doesn't work, but not too many.) So get yourself a good support person who is going to know what to do to help you, a good ob/midwife whom you trust, and learn what you can about relaxing and natural pain management, and I'll bet you'll be fine! All the best!