I would be taking advice from my OB rather than a chiro. Not dissing chiro's, but they don't have a medical degree, or the birthing experience of your OB.
If you were after a second opinion i'd be getting one from another OB, not another Chiro.

But if you have concerns about it, you need to sort it out either way. The mind is so powerful and if you have in the back of your mind thoughts that you wone be able to birth vaginally, then it will undoubtedly effect your birth. So do your research and what ever you decide, make sure you are comfortable and happy with your decision. Best of luck.