Hi, welcome to BW
First off I want to say that even if your friend's babies of a similar age are sleeping well no one has any idea what phases of sleep disturbance are yet to come. They may struggle terribly in the future with certain developmental leaps or dropping one of the naps or no sleep at all due to teething, whilst your LO may breeze through some of these normal phases. Equally they may have other difficulties which no one can predict - we have a tendency to compare to other LOs even though we know we shouldn't. The bigger picture shows that we all struggle at one time or another.
I just wanted to throw another idea into the mix here. I may be wrong with this, just a thought.
You said she was poorly at 4 months and the NW for extra feeds started. This sounds normal to me, even after recovery LOs can need an extra feed at night to make up for lost calories when they were poorly. As example mine (who slept through the night from very early on and was an independent sleeper too) was poorly at 10.5 months old. During and after his recovery he had night waking due to hunger, I was astonished to hear his hunger cry which I had basically never heard due to being on a predictable EASY routine from 5 wks old and he had not even had a dream feed for a few months by that point. He had a real need for those calories, he could not take in enough in the day to make up for his loss during the illness. As soon as he had made up the NW for feeds stopped.
There is also a big growth spurt around 4 months which may have coincided with the increased night feeds being needed (although a GS would generally be a few days) or coincided with the tiem of the illness/recovery which added to the need to night feed.
I also see you started solids around the same time, a month ago. I'm just wondering if you began solids to try to stop the night feeds? And if day time milk has dropped at all since that time?
Sometimes friends or family may advise starting solids to make LO fuller to sleep longer at night but it can have the opposite effect. There are more calories (and fat) in the milk than what she can take in solids and it could even be that she is full on solids in the day so taking in fewer calories in the day, meaning she needs a milk feed at night. It's just another idea to ponder.
If any of this sounds familiar you might want to try reducing the solids a little, maybe even cut the evening solids right down and see if her day time milk intake increases...which may reduce the need for the second night feed.
I think I'd also be tempted to just feed at the 11pm ish NW - it's roughly the time a dream feed would be given and may help her to do her long stretch of sleep after the feed. I know this is slightly contradictory to Kelly's advice above - either is fine really - some people prefer to feed before they go to bed (between 10-11) some people prefer to wait for LO to wake with hunger later in the night. It's really your choice. Mine didn't take a dream feed but still took a feed between 10-11 and did his long stretch of sleep after this (so did I).