It actually looks like you have more of a routine than you may think you do - so that's great! With his feeds at 7, 10, 1, 4,, 6 and 8, it looks like he's on what we'd call a 3 hr EASY with cluster feeding (the last 3 feeds being closer together). Normally by 5 mos, most of our lo's are moving towards a 4 hr EASY, but you've said he's a big baby and eats a lot of milk - how many ounces is he taking at each feed? Would it be possible to add a bit extra to some feeds and space them further apart?
It looks like he's napping for 45 min - that generally indicates being undertired - he's tired enough to fall asleep, but not tired enough to take a really good nap. So instead of keeping him up for 2 hrs at a time, maybe try pushing that a bit to 2 hr 15 min - I'd keep the last 30 min or so really low key - cuddling, playing with one quiet toy, reading a book etc. to help him make the transition from play time to sleep time. Perhaps you could try for a routine a bit like this:
E - 7:00
A - whatever you'd normally do until 8:45, then low key play time
S - 9:15 (start a wind down at 9:00)
E - 10:30
A -
S - 12:45
E - 2
A
S 4:15
E 5:30
A - low key
E - 7:30 - do bedtime routine
That's a 3.5 hr EASY, but moving straight from 3 to 4 may be a bit much for him. As you add in solids, that would happen during the A time, and then you could start moving towards a 4 hr EASY, where he'd have milk feeds at 7, 11, 3, and 7. You could still put in a brief cluster feed at 5 if he needs it.
BW also recommends having a wind down routine - with my dd, we change her diaper, close her blinds - and say "night night outside", read a story, rock a bit, sing a song, and then into her crib. Since your ds isn't used to sleeping in his crib, you will probably need to use pu/pd to help him learn how to sleep on his own, in his own bed (it will be hard, but there's good support on the pu/pd board here). Check out the links I posted, for some info on how to do that.
Does that make sense? I know it's all new to you, but we'll do whatever we can to help out. There's lots of good info here on the boards.
michelle