Hi J..
I realize your post was put up quite awhile ago, so you've probably gotten the help you need...but I thought I'd offer my advice! I've been successfully breastfeeding my son for 14-months now and I hope you've been able to continue b/c as my son has grown more independent it has remained a great bond b/t us and gives us nice quiet time together every day!
That said, I found "The Womanly Art of Breastfeeding", put out by the La Leche League, to be a great book and source of info. So you might check into that.
Your milk supply WILL increase with increased feedings. Your son is not going to go hungry, I promise! Just keep feeding him. I'm not sure if you're working or not, b/c I can understand that with work this could be difficult--if so you might try pumping more often, but again, that could be difficult. If you're a stay at home mom, just nurse, nurse, nurse, and pump when possible, too. Your should notice your milk supply going up in a day or two, mine always increases pretty quick. I know it sounds like a pain, but is has been so worth it for me!
As for diet...I read a lot of responses to your post, women talking about supplements to help your milk...everything I've read kind of debunks all those myths, like having a glass of wine/beer. You just need to make sure you're eating a good variety of food and not trying to lose weight too fast, which I know can be tempting, but losing weight too fast will decrease your milk supply and when your body burns fat toxins are released (which is perfectly normal, many toxins are fat soluble and thus stored in the fat)--too much fat burnt means more toxins in your breast milk and this is obviously not good for your baby. The Womanly Art of Breastfeeding suggests that you can lose about a pound a week w/o interfering with breastfeeding and harming your baby. So tailor your diet to achieve that--it took me a few weeks, but I ended up eating approx. 2400 calories a day while breastfeeding and losing ALL of my baby weight, and then some (nature's perfect diet, right?!).
As for caffeine--I quit drinking coffee and soda while I was pregnant, but a couple months after my son was born, I took up one cup of coffee again in the morning, and it never seemed to bother my son. But some babies are more sensitive--I know when I ate raw cabbage and broccoli my son was miserable (more gas, I think)! And I had a breastfeeding friend who couldn't eat strawberries w/o giving her son diaper rash! So every baby responds to their mother's diet differently.
Ok, I think I've talk enough about this! Good luck! Breastfeeding takes some perseverence, but think of the rewards for your baby!