Glad you enjoyed it and I hope it spurs you on to do more.
Here's a tip for the future, though. You'd enjoy it more if you carried less gear. Essentially you were only out for two nights at a time, so 25kg is excessive. For comparison, I recently undertook an eight week tour, a mixture of camping and motels/B&Bs, I had a shade less than 25kgs of gear, and still came home with items I hadn't used. One simply washes things along the way, and rolls them out in a towel to dry them.
There is no need to worry about your chain. Chains don't break just because you're going up a steep hill, unless they are maltreated or defective they'll withstand much greater force than you can exert. And in the unlikely event that you break one it isn't a disaster, if you carry the right tool (they're light, and cheap) it is easy to fix. Take you about 10 minutes to learn how, and no longer than that to effect the repair.