Having just got married 3 weeks ago I know exactly how you feel.
The planning went on for over a year and the day went super fast and we didnt even get to notice half of the stuff we planned. But the guests had a great time and so did we.
Best advice I can give, book a nice honeymoon early on, and go on it if possible straight after the wedding, that way you have a holiday to look forward to when the planning gets you down. Worked well for us.
Be firm with others, its your day and nicely listen to peoples ideas and suggestions, then do what the two of you want to do.
And last tip, negociate with all the suppliers, seriously I didnt pay full price for anything. The margins they all make on wedding stuff is high so they can always negociate down.
Good luck and all the best - remember it will be a great day.