its early days yet, i think you need to just get more used to the bike and road riding.
What are you used in terms of mtb brakes? large discs?
road bikes brakes are good ... but if you're coming from a large disc mtb, then they aren't as powerful for the same amount of lever force/pull. I find its a different style of braking for the road bike and me personally, i tend to brake gentler all round and kill the speed gradually for corners ( unlike mtb where you can race into a bend and kill speed by grabbing a fistful of the lever )
take time to get used to the hoods. you should be able to brake fine for them for the majority of corners, but for a big descent or stop, then sometimes the hoods just dont quite have the assuredness of bringing down the speed.
big hills are more likely to have you fully in the drops for speed and aero, in which case your hands are better positioned for getting the best pull out of the lever.