I watched your replay, and though I am not an official replay reviewer, I will list some things that could help you.
Basically, I've made a lot of things you did good and a list of things you could improve upon.
-Good forward siege building.
-You deployed the demolisher, which is good. You'd be surprised how many people forget this.
-You got Gloin fairly early.
-At least one of your builders was constantly idle. You should always be moving your builders, even if it's just to the place where you think you'll build next. From what I saw, one builder was doing all the work while the other was slacking off.
-You need to follow up your first demolisher with a fast second one in order to keep your momentum.
-You attempted to fight Uruk-hai fighters with pikemen. This will never work, especially if you're outnumbered.
-It is important to make use of the entire map, not just one part. You only used the center crossing point to charge. Thankfully, so did your opponent, so the mistake was nullified.
-With Gloin you just stopped at the units and tried to kill them, instead of running around them and charging the buildings. Gloin has several powers that are supereffective against buildings.
-You didn't use stances. Stances are very important, and can swing the battle in your favor if used correctly.
Now, as you can see, their were a lot more cons than pros. This is just because I concentrated more on what you need to improve on than what you did right. I think your biggest mistake was not taking advantage of his fortress going down. Note that I don't mean any offense, I am only trying to help you. :)