I had a very similar problem with my son - he also refused a bottle even when it had my breastmilk in it. He wanted the real thing. So, it was far easier for me (and healthier for him overall) just to continue nursing. If you have problems with your supply, just increasing the frequency of feedings (for a short period of time) will naturally increase the supply (it's a supply and demand thing). You might want to contact a local La Leche League group (or use their online resources) as those moms know all the tricks and they might have something that you haven't tried: http://www.lalecheleague.org/resources/assistance.html?m=0,0
They might also have suggestions to increase your milk supply (dietary suggestions, b-vitamins, getting your thyroid checked, etc.).
In my situation, I just decided that I had a smart little guy, who instinctively knew what was best and in the end, it worked out very well. I was even working part-time at the time and had a pager that the babysitter used to page me when he was hungry. And, yes, it is very inconvenient when these guys won't take bottles, but in hindsight, it's such a short period of time to have to deal with the issue. It also may be that he is getting distracted when he eats, so he's not eating enough. I also had that problem with my son and found that I had to go to a quiet place without Dad and big brother around. At that age, they are becoming very interested in the world and might well forgo a meal just to stay involved. My little guy is now 11 and is still a smart, nosey little guy that still has really good instincts about thing. This wasn't the last situation where I've had to adjust my expectations about a situation with him.
Personally, I could never withhold food and I would think that if you were to try that suggestion, you would need to be out of the house to ensure that he knows that that food source is not available. Have you tried this in terms of getting him to take the bottle from someone else? (Note: that didn't work for us - he went all day on his first day with the babysitter without eating, but might be worth a try for you).