I can't tell you if you are making a mistake or not....
If you really think that you will like it; then go for it!
Imho, your hair is cute the way it is!
I can share my personal experience though.. bf I got engaged; I got the same hair cut u want (exact) and darkened my hair. I loved it for a month or so... now, its a lot of upkeep. Now, I am desperately trying to grow it out (bangs and short hair) and its a tough road!!!
My hair constantly looks terrible; I have to keep it up all the time. I personally am not wearing a veil and I can't picture myself without a veil and with short hair on my wedding day.
Alas, I wait for it to grow...
Either way, you have such a cute face - you will make a gorgeous bride! And worse case scenario, if you cut it and don't like it as your day get closer - get hair extensions!