Trust me, when I was a salesman it was hard working with subprime customers because of the time involved. However, sitting behind the desk and seeing what goes into making the sausage, so to speak, I understand the reasons for taking so long.
I will say this, if NFCU or another outside lender isn't able to get you financed, just go into the dealer with am open mind about which vehicle you will leave with. It won't likely be your dream vehicle, but it will get you from A to B. I went through a long credit rebuild myself and I'm finally at the point where I can walk in and buy what I want with a great interest rate, but I started out with a 25% rate in 2012 and went down as my Credit healed. I just financed at 2.49% for 75 months.
It hurts at first. I wish you the best of luck.