I my son is 2.5 monthes old, and until 2.5 weeks ago, he did the same thing. During his 9th week, I took him on a "road trip" to see my family in MA. My sister had said to me that she wouldn't be surprised if the shake up in his schedule wouldn't get him sleeping through the night. She had that experience with her kids, and had heard the same from other mothers. Anyway, the first night, same old thing. He woke up every 3 or 4 hours for a bottle ( I stopped breast feeding after 1 month). The second night, however, he fel asleep at 9 and to my delight and surprise, he didn't wake up until 5 a.m.!! He did the same thing the next night, and when we came home, he continued on the same schedule. During our visit, his normal dialy routine was disrupted. He didn't get to nap all the times he normally would, because there was so many people around and so much going on, he wanted to be part of it all. I don't think it would take a road trip to do the same thing, just some day trips to disrupt the napping schedule so your baby is more tired at night.
By way of background, and I'm not sure how much this matters, but durng this time, he was sleeping with me in my bed. He would never go to sleep in his bassinet, and I didn't want to put him alone in his crib yet, so he slept by my side in a boppy lounger (not boppy nurser) and my husband slept on the sofa bed. We went to doc las week and she said it was time for him to go into the crib. I told her it would never work, that the only way to wake that baby from a sound sleep was to lay him in his crib. She said that I had to put him down awake but drowsy. To my shock, she was right. FOr the past week, he has a bottle at 7:00, then a bath, a massage with lavander lotion, and I lay him in his crib. He just hangs out talking to himself for about 30 minutes, and falls asleep on his own. He sleeps until about 5. He does fuss a bit around 2, but I just do in and stroke his head or hold his hand for a minute and he goes back to bed.
Also, this may make a difference, is he was drinking 6 oz. bottles every three hours. Now he has 5 7oz bottles betweek 5 am and 730 pm, which is 35 oz per day. THis is likely how he can go all night without feeding.
Hope this helps!!!