You do have a big eater!! Our lo was like that and still is. At his 2 month check up he was 15 lb 2 oz. When he was 3 months old he was still waking to nurse. Anyway, at his 3 month appt my doctor told me that he does not need the calories and was just waking out of habit and had learned to be hungry. He told me to let him cry it out. I thought he was nuts (I didn't tell him that though) There was no way we were going to CIO. Anyway, I picked up a copy of Ferber's "Solve YOur Child's SLeep Problem's" or something like that anyway. He suggested the following and it worked after three night, I kid you not!
If breastfeeding, when lo wakes to nurse, decide how long you will let him. I picked 7 minutes. So on night one I let him nurse 7 minutes then I took him off....he was not happy. Yes he cried but I held him through it. He cried about 3 or 4 minutes but it felt like sooooo much longer. The next night he woke and I let him bf for 5 minutes.....he cried, I held him, etc. The third night I let him nurse for 3 or 4 minutes (can't remember), he cried (not as much). The fourth night .......... nothing....seriously! The author of this book recommends the same with bottle fed babies except that you'd reduce the amount of milk by an ounce every night over a period of a week. We were lucky that it worked so quickly. He's 11 months now and has not woken to nurse since except when he's been sick and that was my doing
I think if I had tried this when he was older it may not have been so successful because he'd be more ingrained in habits. I do totally agree with the growth spurt possibility though...especially if you notice him sleeping more. However, it is your judgement. I seem to even remember in Tracy's 1st book even that she said a baby of 10 lbs (I'm almost positive it was 10) does not need calories at night to sustain him. Anyhow, after doing this I totally agreed with my doctor that he had learned to be hungry at this time(habit) but I was definitely not going to let him cry it out. Anyhow, just thought I would share what worked for us.
Zelka