I think you might find it helpful to look at this sticky on the 'gentle removal plan'. It originally comes from a book called 'The No-Cry Sleep solution' by Elizabeth Pantley (there is a version for toddlers and preschoolers) but it is also used by Tracy in BW for toddlers (the case study on Leanne).
https://babywhispererforums.com/index.php?topic=52857.0The idea is to gradually teach him to fall asleep without the breast. Then once he has mastered that you could move to something like pu/pd - walk in/walk out as the older child version.
I think when an older baby is used to nursing to sleep it's best to begin with gentle removal as it can be such a deep seated habit. If you suddenly just disappear the boob they can become very confused and literally not know how to fall asleep without it.
I agree it would be good to look at a new routine - develop some key phrase you can use that sends a sleep signal or a little song to help the transition. It sounds like he may have a bit of separation anxiety if he no longer wants to fall asleep alone. I would definitely wean him off nursing to sleep first and then later you can 'wean him off' needing you to be able to sleep if you want to.
It sounds as though he nurses to sleep in the day if he's overtired so I guess an obvious point is to try and organise his napping routine so he doesn't get to that point.
I'd also agree about trying to increase daytime calories while also reducing the nighttime ones so you can be confident he isn't genuinely hungry at night. You may find DH could be a big help with weaning the 2am feed.
You could also come and visit us on the extended nursing thread as you may find some example of people 'night weaning' on there (but not weaning entirely as that is discussed on the weaning thread).
Good Luck.
Tell us a bit more about what you'd like to achieve - how many nursing sessions in the day? Do you want to keep the paci?