F.A.
Hi there T.
No, it is not unrealistic to expect a 7 month old to sleep through the night. Both my breastfed babies were sleeping through from about 3 months (from 7 pm til about 5 am, then a feed and back to sleep). The 7 pm til 7 am sleeping started as soon as they were off the breast and on a bottle at about 5 months.
I don't think babies of that age need to feed overnight, and you need to be careful that you are not just getting them into a habit of waking up at night and then needing help to go back to sleep. Falling asleep on their own is a skill they need to learn along with everything else and the longer you leave it the harder it is.
The main thing is to ensure they are awake when they go to bed at night, though relaxed and drowsy, so they get used to falling asleep alone. Also, don't go to them in the night for every whimper - leave them to see if they will settle on their own. I am amazed the number of parents who effectively wake their kids up at night by rushing in at every little sound.
I didn't need to use sleep training but if you do, I believe it works and won't do a child any harm. Otherwise you can be letting yourself and the baby in for years of broken nights which does no-one any favors. Good luck!