The real way to get damage out of leap attack is by taking shocktrooper, which means you'll likely have negative AC after you're through charging something. It sounds like this isn't an option for you, though. You asked for ways to improve your damage, and outside of more nifty gear, the fastest way to do that is holding something in two hands and power attacking, preferably with shocktrooper and leap attack. Your int is too low to be a tripper or disarmer, unfortunately. You may just get stuck with being a tank without the dps.
Eh, I just feel like I'm throwing out generic min/max advice that requires you to scrap your character concept and instead be a giant psychic robot who likes to mario jump things. I wouldn't take paladin past whatever level gives you charging smite, and just pick up an extra smite feat or two. Going into something psychic incurs multiclassing penalties, unfortunately, and you have that Eberron feat that let's you go back into paladin.
how to always win on a skill check
So let's look at the total:
1d20 + 8 + 2 base str + 1 magic str + 5 item + 12 haste + 1 luck - 8 for being awesome = 1d20 + +21. Of course, this hinges on having haste on before you charge. Boots of speed are never a bad item choice. With the haste and str alone, no other items, you have +14 to jump checks.
Not a 100% sure thing, but investment in these items (pearls of power, gauntlets of str, boots of speed) have much more utility outside of jumping. The biggest loss is the skill point sunk into jump.
Oh, and then you could always have a [url=http://www.d20srd.org/srd/spells/jump.htm[/url] Jump spell put on you before combat for a bonus that stacks with all mentioned above.
Now, on a roll of 1, we're getting jump checks of 52 at level 9 with all of the above! And this is without feats, races, obscure spells, or incredible speed increases! Just make sure to take some ranks in the exemplar prestige class (complete adventurer) so you can use that jump check as a diplomacy check! You can now jump over the fire giant king and turn all his hostile subjects to friendly as a move action.
Those spells can all be cast from relatively low slots (1st to 4th), and when they offer a save, either still have an effect, or affect an area, meaning multiple enemies can be hit with it. Even if they make their save 50% of the time, it's a low level spell slot that makes your job a heck of a lot easier. Much of the time, buff, debuff, and control is a better route for the party casters, as it means their tank becomes much more effective.
Ugh, that just turned into "how to play a caster." Sorry.
/puts it in a room by itself