Just to be 'statistics woman' for a moment. BM has both a higher calorie content and a higher fat content than commercial formulas - not by a huge amount but there's a slight difference.
Human milk 22cal per oz, 1.2 fat grams
Formula milk 20 cal, 1.06 fat grams
That's an 'average' so at some times of the day and during a feed milk will be obviously higher and lower in fat content.
I think if you are dealing with some patterns and behaviour at the breast you need to address those rather than change the milk. Plenty of bottlefeeding babies have night wakings and feeds.
I agree he might be ready for longer intervals in the day if he's not interested at the 3hr mark. Perhaps check out the EASY board for transitioning to 3.5 or even 4. You need to try and increase his feeding effectiveness in the day as you suggest. I'd also agree with trying to minimise distractions in the day.
If you feel he's not working hard enough at the breast you could use some breast compressions to help him reach the hindmilk:
https://babywhispererforums.com/index.php?topic=88759.0If you need to change sides to keep him going - you can always return to the first side again for the hindmilk. There will be a new letdown richer in hindmilk. Infact you can change several times if you really need to.
DFs can take a few days to kick in so don't give up on that just yet. You may need to play around with timing.
Babies at this age don't self-wean and 'lose interest' although the world does become very interesting and bfing can sometimes lose its status in all the excitement! It's not a phase that lasts forever but a different routine and trying things like breast compressions may help.