Hi,
My milk supply was usually ok, but one time we had a terrible bout of thrush and it dwindled down to next to nothing. Do you have a breast pump? What worked best for me was to pump immediately after feeding my daughter, even if barely anything came out as she'd drunk it all. This helps stimulate your body to think it needs even more milk. Some people have good luck pumping on one side while their babies nurse on the other, so they automatically have letdown. I was pumping at work anyway in addition to nursing while we were at home, but I increased the frequency quite a bit as well as how much water I was drinking (like 3x as much till it built back up). I should say she was about 5 months old when this happened, so needed to build up a lot, as she only was receiving breast milk at that time.
If you don't have a pump, I'd suggest definitely not stopping him if he's not done (some people suggest getting babies on a schedule at this point, but it really doesn't help milk supply). You may already be feeding on demand, but if not it's really helpful to do so at this age. He's the expert & will stop when he's had enough, so there's no need to try to get him on a feeding schedule or anything at this point. Also, he's at an age when many children experience a big growth spurt so he might just be needing a lot more milk & you're noticing it.
What have you already tried? I don't want to give you any unhelpful advice. I just know how great breastfeeding can be, though, so I'd love to offer any other suggestions I can if they'd be helpful.
Good luck! Write back if you'd like. Here's a link you might find helpful: http://www.kellymom.com/bf/supply/low-supply.html
You might have to cut & paste the link if it doesn't show up underlined here.
Take care,
G. in Lawrence