Hello Erum,
I am sure you will win it!
I did mine without a lawyer and brought my cousin as a witness. They did not even speak to him as I answered all their questions.
It took around 3 hours, they asked lots of questions about dates we met, where we went, specific things that you should know about your spouse. Also they questioned my wife friends, family etc. They asked questions from the blue book, so make sure you address any reason outlined in your blue book on why they rejected you, be specific, honest and straight to the point. Make sure you know any little details about your spouse etc. Just read the blue book well enough and your answers must match with your spouse.
If you need any help, you can message me.