First of all, I want to congratulate you and your wife on your conversions (however long it takes for the both of you). Secondly I want to advise you to calm down: just keep calm and pray!
In many cases, the fear that you are describing is from the devil. He will always try to keep you down, he will try to keep you from the church, and he will try his best to lead you from salvation. Im no monk but I think that what you have described is a form of temptation. Sometimes we can accidentally think too much. Orthodoxy is not a game, your wife isnt beating your score, and your definitely not behind. I advise you to talk to your priest
and talk to your wife. The catechumenate stage usually takes a year (for some people, the catechumante stage could be longer or shorter). Concerning the chanting: Not everyone has the vocals of an opera singer or of a middle eastern maqam singer, thats okay! You dont have to sing well (as long as you arent in the choir), I know many people who dont even sing at all! May God guide you and your wife on your journey to the Church.