First of all, your milk supply won't necessarily go down when you starting pumping more, etc. I have a couple of friends who because of problems with latching, etc. ended up pumping exclusively and were able to have enough milk to keep their babies in breast milk for over a year. The more you pump or breast feed the more you will produce. I would add one or two additional pumpings now, in between feedings. So if you are nursing every 3 hours, then pump and hour and a half after nursing, nurse again an hour and a half later pump an hour and a half later and nurse an hour and a half later. You would be surprised that in just a day or two your milk will adjust. In addition, there are lots of things that you can do to help boost your supply like mothers milk teas, limiting caffine, drinking lots of water, etc. There is a ton of info on the web re boosting supply.
But the bottom line is that with the stress of work, etc. lots of women's milk does slow down, but you have to cut yourself some slack. Even if your baby has to have a bottle or two of formula a day to supplement the breast milk, he is still getting the benefits of breast milk. Also if pumping during the day doesn't work, that doesn't mean you can't nurse in the morning and at night. My some continued to nurse in the morning and at night for two months after I stopped pumping during the day. Each kid is different and you will have to just try it out. Just don't be too hard on yoruself if you have to supplement. I would definitely add extra pumpings during the day now, though.