Hi Wendy
How did you get on at the doctors? If you start to feed him little bits here and there throughout the day, he will turn into a snacker, has this been happening long? It may already have happened. The best thing to do is perserve at the 'designated' E time, DS can also take an hour sometimes. Is the teat fast enough, is he free from distractions when feeding, have you tried giving him a 5 - 10 rest after the initially 3oz?
You need to be choosing a wake up time and sticking to it i.e 7am. This means that your feeds will always happen at the same time everyday. it is excellent you got him back to sleep after the 6am wake up, anything before 7am should be treated as a n/feed, but you should wake him at 7am to start the day. I also notice your bedtimes are varied, this is making the wake up times varied.
I really, really feel that you should be waking up at a set time and getting him to bed for the same time everynight. Babies like to know whats coming next, and having the, on a routine that is roughly the same everyday - helps with this.
Let me know what you think.