What Brandis R said ; ) And I'm adding a few things:
Looking at Earth's Best and regular Enfamil Lipil, they both have the same sweetener, which is lactose, milk sugar. It appears that Similac Organic has added the evaporated cane juice which is baiscally, sugar. It did not go through the refining process but it still is the same ingredient, sugar. It is used a lot in natural foods so people think they aren't eating sugar, but they are.
Regular Enfamil Lipil is pretty similar to Earth's Best as far as no other added sweetener, but it is not organic.
If you look at the carb counts on all of these (including the Similac Organic), they are all similar, but I would still be wary that it is adding extra sweetener (the cane juice) that is not needed.
Even with all that being said, I highly doubt your 2 month old is growing too fast because of the extra cane juice. I'd probably switch formulas because I don't like that ingredient, but your baby sounds like his size is fine. His height and weight are proportional. Of course he is growing fast -- he is an infant and they go through NORMAL growth spurts.
I would also advise against using any type of homemade formula. It is difficult to replicate the proportions that are used in the formulas, and this balance is crucial to health. The Earth's Best formula seems like it would be the best. Wish they had that when my kids were babies.