Thanks girls. He sleeps in his cot in our room. I'm lucky my DH is very supportive - he has no problem getting up to do the bottle feed (I'd prefer it was EBM but I have to recognize my limits and trying to express is just not possible right now, but I figure after 5 months exclusive breast milk that one bottle a day can't hurt him).
I'm not sure how I feel about co-sleeping but it certainly may come to that if he doesn't start sleeping a bit more.
We still use a nipple shield to feed too. I've tried to wean him off that but it hasn't worked.

I can't imagine continuing to feed this much for another year ha ha!

I checked his chart and he has dropped from the 50th to under the 25th percentile for weight. It's very hard not to second guess yourself, and also you always think you need to "fix" it. It's not helping that I know two people with boys the same age and both their babies sleep through the night. I know all babies are different of course, but sometimes the last thing you want to hear is how "good" someone else's baby is and how they slept 12 hours last night (when you were up 5 times).

Anyway I think I'm rambling now so will stop and try and enjoy a few mins rest while both kids are asleep...