Disclaimer: my advice could get you fired. :)
If you really want a definitive answer, I would call your boss like NotMe says. However, considering it's your sister's wedding and it seems like your boss doesn't care enough to respond, you don't really want the answer to be "No." In my experience if there's a problem with taking vacation, your boss lets you know immediately.
So I would forward your previous email along with a new message to the effect of:
"I have not yet received a response, so I assume that my leave request
has been approved. Please let me know if you have any issues or
Include in that email with your contact information while you are away, and explain what plans/preparations you've made to have your tasks handled in your absence.
It's risky because you don't truly have an affirmative response from your boss, but hey, it's your sister's wedding we are talking about.