It takes time for a routine and the slightest change knocks it out completely. We are baby led at the moment and that works for us as he's a complete breeze (luckily). He barely cries, wakes with a smile and is all round a happy baby so we don't mind the 2 hourly wake up call. I appreciate we are in a slightly different situation so my advice to you is get yourself into a routine and stick with it. Routine is key for making it work for you.
When we first started to feed with the bottle he would refuse and wanted breast. We introduced bottle throughout the day and I (the Father) would feed him so he knew there was a change in how he had to feed. He now takes bottle whenever we give it to him which helps with night feeds. Catching them before they cry is what you want, this way they are in a better state for being bottled fed.
Our baby is 6 months in a week. He goes to nursery and has been since he was 3 months and the kid is full of energy. He naps about 3 times in the day and often no longer than an hour each time and he is up every two hours for a feed.
What I have noticed however is that if we do give him a bottle he does sleep longer. He can take about 7oz from the bottle and I bet he only takes half of that from the breast so with bottle he's full longer. We put him down about half 9 at night now and at this point we breast feed. I've suggested to the Mother that we take a bottle to bed to give to him when he wakes up at around 11pm for his next feed. When he does we should see 4 or 5 hours sleep which would be a massive bonus for us. As I said above, catching them at the right time will go in your favor. If you can feed before they start to cry then you have an advantage otherwise they will also look for comfort which is what the breast offers.
It might benefit to take a bottle to bed with you. You can get warmers that keep the bottle warmer for longer. We have yet to invest in something ourselves as we are still working out if this will be required. A quick Google brought up Babymoov Travel Bottle Warmer as an example of what I mean. This might be a quick way to get a bottle without the baby waking up fully and starting to cry for food. With a bit of luck they'll take it without a fuss, go back to sleep and stay longer. At least that's what we are after so will be interesting to see this through.
I'd be interested in other answers as I feel like we are in a very similar situation. I will revisit my answer as well and update with how it goes with us.
Edit; we gave a bottle to our baby at around 1.20am when they woke up. Prior to this, Mother had breast fed at around 11pm. He took 4oz so not as much as I'd like him to take. He slept until around 5am so longer than we would expect. We need to work on our routine a little but it did help for him to sleep a little longer.
Edit; he can have around 6oz out of the bottle now and is sleeping a little more because of it. If he is unwell which he has been then the pattern is disrupted but quite often from about 8 he's sleeping every 3-4 hours now and every time we just bottle feed him until the very morning (we get up about 6am) when Mother breastfeeds. We are finding that his sleeping is extending, albeit slowly so will give it another few weeks to see how it pans out. It does seem that by sticking to a routine the sleep is getting better. We don't force it though. If he is wide awake at 8 we don't try and put him down. We wait until he sleeps and then go from there.