elliotlove I was going to suggest a fast nipple before I reached the bottom of your post
If that is too fast try and put a small hole in the current one you are using so you have a happy-medium for a while- he should not gag on the teat because of fast flow milk.
He could also be waking at 5am becasue he thinks that is his wake up time, you say you have in in bed at 1830.
It is common for LO to be up twice a night at this age, mine was - he has only recently started sleeping through.
How long have you done a d/feed?
Have you tried a night without the d/f to see if he still wakes at 1 or 2am - I never did a d/feed for this very reason.