i started this game yesterday and i think ive done decent for my first try at noble. at this point im not sure what i can do to catch back up im playing as augustus and i just finished off alexander. before attacked alex i was nearly the tech leader and was allready the most powerful nation(mostly do to buildng a lot of CR2 praetorians to upgrade to gunpowder units before they were obsolete.)

One thing that can help you is to develop large cities. Simply put, you have over-cottaged and not implemented a food plan for many of your cities. Case in point;

http://www.users.bigpond.com/c.hills/cumae_food.jpg

With Biology within grasp I'd start knocking over a lot of your unworked cottages and develop a plan to grow your cities food-wise.

You have however overcome the biggest hurdle of playing Rome - early game over-expansion and consequent crashing economy.