I understand what you are going through! I've had over-supply issues with DS too (right up until we dropped to 2 feeds a day). When DS was about 10 months, I actually took dried sage 3 times a day (1 tsp) for about a week. I just put it on my tongue dry then washed it down with a glass of water. It made no difference (apart from giving me a metallic taste in the mouth).

3 weeks is pretty early to be worrying about over-supply though. I've read it can take up to 12 weeks for things to settle down.

How do you know that Xavier is getting too much foremilk?