personally I think once you mention GF on here you won't get any advice other than the attacking of GF.
It is possible for 5 week babies to get into a routine at this age, I know this for a fact as I'm a maternity nurse and I have gently eased ALOT of babies into a good routine from around this age, without the use of controlled crying.
JOJO, my advice is see what is happening in the day, you say your baby is sleeping most of the morning, as he is awake most of the night, he will need to catch up somewhere.
but be careful you don't get into a vicious circle and the baby sleeps all day.
Its not true that its impossible that babies of 5 weeks can differentiate between day and night, they so can, however they need us as parents to show them how.
It takes time, but try and keep your baby's sleep in the day to max 5 hours, roughly about 1-2 hours in the morning, 2-3 hrs at lunchtime and 30mins -1hr late afternoon. Try your very best to keep the baby awake after 5pm as this will ensure your baby goes down nicely at 7pm, if you want your baby to go to bed a bit later then obviously they can sleep past 5.
If your feeding every 2-3 hours during the day and getting 5 feeds in between 7 and 7pm then Yes a baby can go from 7 til 10:30 for its next feed.
2:30 is also about right for this age for the night feed, which your ds does, so this is brilliant.
I'm sure once you work on waking him during the day , he will settle again at 2:30.
I'm sure you are but remember to keep the room very dark and quiet for the nightfeed, and a cuddle back to sleep at this time might really help.
I hth , trust me, through years of doing this for my job and 2 children of my own. It is possible, I know when your exhausted its hard to see the light..but its there!