I don't have anyone to walk me down the aisle?

If you have an uncle you are close to, or if your grandfather were still around, I'd suggest asking them to give you away/walk you down the aisle. How old is your brother? If he's over the age of ten, and you are close to him, then I would say ask your brother to walk you down the aisle. Do you have any male best friends, important male figures in your life? Sit them down, tell them about your predicament, and they'll probably be gung-ho to walk you down the aisle. If all else fails, you could do something new and have your fiance, soon to be husband, walk you down the aisle.