It may not be your sail trim as much as your driving. As the wind and waves come up, you do NOT want to be pinching the boat. Pinching (pointing up too high going up wind) is a very common trait with new sailors as they use that to depower in a gust, vs. easing the traveler down, keeping the bows down and going FAST.

If you are pinching you will know because even in big wind your speed will not be all that great and the boat will feel sluggish. So try easing the jib out a bit so it doesn't backwind the main, and travel the main out about a foot, and keep the bows down a bit, do not pinch when a gust hits, ease the main sheet instead, and you will go much faster. BTW, if you are racing, it is usually "faster" to go low and fast than high and slow to the A mark.

When the Alter Cup guys are talking about "Sawing the Main" that's what they are doing, easing the main in the gusts and then quickly trimming it back in as they accelerate. It's best if the crew does it so you can steer in a straight line, not zig-zaging all over the place.