Yeah, the reason you’re kneeing yourself in the chest is because you can’t achieve the pelvic tilt that the pros can when they run lots of bar drop. That mostly due to flexibility.
Although most people who can put their hands flat on the floor can tolerate more than 6cm of drop. 6cm is by no means a small amount, but it’s definitely not loads – unless you’re really short, then it could be quite a lot. However you may have long arms or poor glute flexibility (or both), thus meaning the greater drop doesn’t work for you.
You shouldn’t have to slam your saddle forwards to achieve the position, that’s usually something you do when you’re running too much drop for your glute flexibility.
That’s me in the kind of position you’re suggesting, knee is a few mm behind the pedal axle. https://vimeo.com/87893932