Of course an experienced lawyer could help you, but I am not sure how far a one in US can help with your consular processing.
I think all in this forum understand your anxiety and I am sure they join me wishing you good luck !
From your previous posts it is my understanding that you have the 'safety net' of an approved H1B petition with you to get back to US, in case anything negative happens to your DV-GC case.
If you get the DV-GC ONLY for you now, it may be harder for your wife to apply and get a F or B visa due to 'immigrant intent'. But if she can try H1B on her own then that is a possibility.
But if you want to really marry her now, and really want to take her with you to US without delay.....then.....SIR, the ball is really in your court with you and you need to play it..... one way or another!!
If the above is your determination and NO STRANDS OF FRAUD is involved with your intended marriage, then have faith and act boldly. i.e. Postpone your interview, marry and get the legal documents and send copies to KCC and re-schedule. Go to the interview with your heads high and you will be fine. In this scenario, remember that you can not go to the interview without KCC confirming that they added her to your case. **** If that fails, you can go ahead with your H1B applications to get back to US, both of you. (of course nay-sayers can give all sort of scenarios what can go wrong with your H1B application too !!)****
Well, if that is NOT your determination, then your options are pretty easy but may be difficult to swallow thinking of her plight. Then go get your GC without trouble, marry her and then worry about other legal ways of getting her to join you...sooner or later!!
The point is, if you want to follow the first route, all it needs is your courage and faith.....'cos unless and until you go with that scenario and face a consular officer yourself, no one can predict the outcome.
But as few others have said, the law is with you and you can add your new wife to the case and be completely safe with your interview.
Good Luck !!