Not killing anything is much harder than it sounds; for one thing, leaving fast travel occasionally puts you right in the middle of a herd of animals. This occasionally leads to an odd situation where the animal suddenly notices you standing there and lashes out automatically, which can prompt a counterstrike. If it's a small enough animal, chances are good that you'll strike it down instantly or injure it enough that it will die shortly afterwards. Birds are especially prone to this sort of thing.
Now, if you choose to eschew the use of fast travel and decide to just walk, you have to constantly check in front of your adventurer to make sure that there aren't any animals in your path as it poses the same risk of blundering into an animal by accident and killing it entirely by accident. Keas for instance. Not just sneaking either as your adventurer will need to look up or down ramps to avoid animals below or above him/her. The best thing to do there is to stick to level ground as much as is possible. Same for crossing rivers. It takes FOREVER to walk long distances as well so be prepared for hours of moving short distances that allow you to look ahead enough to avoid animal encounters; it took me several hours for Nish Koltulon to hike across the Bronze Towers for the Dawn of the World challenge in this fashion and that was only about a quarter or so of the map.
Far as food goes, the best option is to simply sell your weapons and purchase as much food as possible in exchange for that dagger and default weapon as that part of your life is now over. It might even be best to take sword/axe skill and a level of shield user just to have more to sell; that or slip into a catacomb just enough to regain some treasure. Inflicting harm on others by stealing from them ought to be right out as an option, but recycling or recovering goods from thieves shouldn't be. Especially if you sell them at well below their normal value since you can't actually give them to somebody right now.
An entire stack of plants at the market is enough food for months and you can always sell the seeds at a later date. Meat is much less of a bargain because of this. Barring buying a walking stick or another flask, the rest of the money should probably be given to a shopkeeper at the end by overpaying for whatever you buy as attachment to worldly goods like wealth doesn't really fit the idea.