Generally inquisitors are the ones that support the characters that charge headlong into the fight, not take on that role themselves. The class doesn't tend to be optimized for such tactics.
That said, the inquisitor is a master tactician. They use tricks and buff/debuff spells to give themselves an advantage in battle, and specialize in exploiting the opportunities created by their allies to their own benefit. They don't necessarily do the heavy lifting, but make it look like they do. In more general terms, think of the average inquisitor more as a bard or rogue, rather than a barbarian or fighter.
Now, if you want some advice on your existing character, we're going to probably need more information. Posting the entirety of the character is ideal, but barring that any additional information, especially feats, spells, and any non-standard abilities you may have, would provide us with a better picture.
Here's a helpful thread about Inquistors. Note especially Ice Titan's suggestions. But I don't understand why with those stat's you're having much trouble. Heal up between fights, know when to retreat (even if just to cast a cure and go right back in the fray), and get some decent armor, probably Breastplate at your level. Are you the only tank in your party?
Inquisitors are great in combat, that's their thing. At low levels they lack the staying power. Judgment doesn't do much and you only get once per day. Once you get to 5th level though the Inquisitor starts kinking into gear. At 3rd you are still kind of weak but things really get better after 5th and from 5th to 10th you really start to shine in combat. I haven't gotten farther than that with my Inquisitor but I definitely can keep up with the Full BAB classes in my group.