Sometimes what happens with a big growth spurt is that his needs just keep accelerating faster than your body can compensate. So then you would get the scenario you describe - you seem to catch up, then he still needs more. You supply is not rising and dipping, it is just not rising quite as fast as he is growing.
The more you feed, the more it will stimulate supply, but adding more frequent feeds (at 1 hour) may make him prone to snacking if it goes on for several days - and then he will take less at each feed, which then will make your supply dwindle again.
I pumped IMMEDIATELY after the feed for 15 minutes when I was relactating - that worked well. I didn't get much out, but it sent the signals. It also gave time to build up milk for the next feed. (and gave me the opportunity to do SOMETHING other than feed or pump)
Are you using breast compressions at the end of the feed? This may keep him interested for the third or fourth "side". I assume when you say "20 minutes" or "10 minutes" this is how long he is feeding, right? You're not stopping him? Just letting him suck as long as he wants is going to work better than a pump.
You can also try a galactagogue - I like a tincture called "more milk plus" that has fenugreek + blessed thistle. Fenugreek tablets also work and may be more readily available. Drinking lots of water and getting as much rest as possible are vital.
Some other foods that have been recommended anecdotally for boosting supply are:
1 cup of coffee per day
a daily bowl of oatmeal
lentils and chickpeas
curries
Hope this helps!
