Hi H.!
I couldn't help but laugh at this request because my name is H. and I had the EXACT same thing happen to me last year. It was AWFUL! I did the same things you've done, even down to having the van carpet professionally cleaned. And for anyone out there who thinks Lysol "kills odors," don't even go there with spilled milk on carpet! My kids were literally hanging their heads out the windows to escape the even worse smell I'd created trying to "fix" the situation.
Now the one product that finally worked for me was OdoBan--and it worked GREAT. The only thing I can guess with your situation is that somehow, you may have missed some crevices or the milk dripped through to somewhere you haven't attacked with the OdoBan yet. But once you attack it with the OdoBan, it really should work. I'm so sorry this happened to you--I know how awful it is. Good luck!