I was gona say... I am a pretty mediocre sailor and an 18 vs a 14 shouldn't be a race at all... Under the right conditions a 14 might be able to match speed (briefly) on a reach... or even running downwind.. Just for a second.. But pointing upwind.. Not a chance. At least that has been my experience vs a great 14 sailor..
I haven't really done any serious racing with an 18 vs a 16, but played around plenty last year.. and the differences are minor enough a good 16 sailor could outrun an average 18 sailor on a course, no doubt.. But all things being remotely close the equal the 18 is so much faster on a course simply because of the ability to point. Enough so that a lesser skilled sailor should be able to keep up with a better 16 sailor short of major tactical errors. At least this was my experience.
My first thought after reading the first post was you are running to much rake. There is no need to rake an 18 back to put the center of power closer to the rudders to make it point... You can use the extra 'power' on the 18... Stick the bows down and drive it hard... but you have the book now so ya probably figured this out already..
And also... I would guess with your sail raking it back would hurt you even more than raking with a stock sail...
but then... ya know my advice is worth what you paid for it.