Damage Resistance Weapon and other... stuff

[Darth That Guy]

I am plunging into a epic fantasy level 13 Pathfinder Campaign. I am new to pathfinder but played a little bit of D&D 4e and 5e. I have built a fighter that is decent at close range, medium range (reach) and long range (crossbow). But my DM says my AC is too low and that I need to find ways around damage resistance, such as weapons with good alignment, cold iron, etc. Problem is, there's not much else I can do AC wise. Here is some highlights of my fighter:

Human Fighter
Level 13
(15 feats total)
Campaign: Curse of the Crimson Throne
Mode: CRB and APG ONLY

AC: 30 ... 10 + 2 (dex mod) +9 (full plate armor) +5 (magic enhancement of armor) +2 (Ring of Protection) +2 (amulet of natural armor)

Weapons:

1. Great Sword (magic enhanced +3)
2. Lucerne Hammer
3. Heavy Crossbow (repeating):
4. Crossbow Bolts: 60
5. Screaming Bolt: +2 bolt screams when fired, forcing all enemies within 20 ft of the path make a DC 14 Will save or become shaken.
6. Heavy Flail (Magic Enhanced): +2 Disruption special ability against Undead creatures. Must succeed on a DC 14 Will save or be destroyed (8,000).
7. Regular Great Sword
8 Pilum x10
9. Chakram
10. Spear

I only have starting wealth of 140,000 GP. I bought potions, elixirs, wonderous items (Belt of giant strength and headband of mental prowess).

I am trying to build a fighter that is good at three offensive things (close range, medium range, and long range) instead of extremely good at only one particular thing.

My two top priorities are:

1. Armor Class. How the heck I can get it past 30.
2. Bypassing the damage resistance of enemies via cold iron, good aligned, and etc weapons

Any ideas? I'm willing to discard all my weapons in order to get my AC straightened out first.

[Hawktitan]

As far as AC goes it's not going to be easy.

Firstly you could up your dex, change your belt from a str belt to a str/dex belt.

Dodge feat.

You could primarilly use a meteor hammer - an exotic weapon - for a +1 shield bonus that you should be able to keep up most of the time. The weapon is kind of a cool and very versitile in and of itself as well.

Making those changes would net you +3. The only way I see it going higher would be to use the combat expertise feat or fighting defensively while you fight.

As far as bypassing DR, it's not as bad as your DM makes it out to be. A +3 weapon bypasses DR of cold iron and silver. Keep a couple oils of Bless Weapon on you for when you need to bypass DR/Evil. Then making your weapon admantine (or just one end of the weapon in the case of the meteor hammer) you'll have most of your bases covered.