my dd started off this way too. i finished reading bw at 2mths old....but she would already sleep 730-330. i tried to df (bf too) with expressed milk, but found i ended up with many many nightwakings instead of the one time to feed.
if you don't mind getting up once to feed, i would keep it the way it is. if you can get her to df and have success, great.
i too think it is easier to drop/push back the night feed than it is to wean the df, OMO.
sami