*I apologise for my first answer, I thought you said your three and a half WEEK old. Sorry -
Yes, your breasts will swell up and leak. And you may end up with mastitus if you are not going to pump it out while you are away.
Also, if you have been given the ok by your doctor at the 6 week check it is safe to have sex!
Good Luck and have fun =]
*To the answerer under me, are you not aware that breast feeding relies on supply and demand?
If you don't feed, even just for three days, you become engorged, you may end up with mastitus which is AN INFECTION IN THE BREAST MILK, and then your supply drops. I don't see how 'binding' your breasts makes any difference what so ever to that FACT.