CF is brutal, no doubt about it. The question as to whether or not it's "too brutal," though, is up for debate. I'm no vet, but I think that it's just about right. Others may disagree.

As far as finding a group goes, I'm surprised you've had difficulty. Granted, a thief is not seen by most as an "ideal" groupmate, but unless there were some RP restrictions in place, a level 16 thief should be able to find a group without a problem unless you're playing odd hours, at least in my experience.

As for food, you say "if I'm not killing I'm not earning" and that couldn't be further from the truth, especially for a thief. A lowbie thief should never worry about having enough gold. There are ways that you can gather literally hundreds of gold as a lowbie thief, so having enough copper to buy food shouldn't be an issue. And if no one's willing to help you figure out how, there are plenty of areas with food just laying on the ground, free for the taking.

The rewards of CF are tremendous if you can ascend the steep learning curve.

If some of the problems you're encountering are because you're playing non-peak times and there's only 8 people online, there's not a lot to do, but much of the rest of the stuff should be easy enough to address.

Good luck.