This was a solo ride? Not a organized Century Ride.

Either way you did what you could do. Unknowingly, due to the unexpected terrain, pushed your limits. So good for you. Especially since you seem to have figured out the stuff that held you back. It'll be better next time. Don't wait too long to tackle the hills again. You need to experience them so your body will know it has to deal with them. And you'll learn certain things to do that will make them easier.

On those hills, you need to make sure you can pedal in a gear ratio that is just as easy as when you are on level ground. And your cadence is just a fast as cruising. Only when you are in your lowest gear ratio and the hill gets steeper should your cadence slow down. For the short hills in my area, I usually go up them with a faster cadence than I cruise at.