Sorry to hear of your awful experience. I can certainly understand why you don't want to repeat that.
If your hospital is not supportive of a VBAC, then doula or no doula, I think a private midwife (and aiming for a HB if possible) is probably your best bet. A doula can offer support to you, to help you during labour, but she cannot advocate for you on medical issues, whereas an IM may be more supportive of a VBAC to begin with and can support you both emotionally and medically.
All the best to you