I'm struggling to determine the prices, weights, and capacities of my Large PC's gear.
For example, weapons seem to cost the same, but armor costs more. Most other items like clothing don't mention any change, yet some hint that there is a difference but don't say what that difference is exactly for Large creatures, like the waterskin and the belt pouch.
Do the rules cover a Large creature's gear, and, if so, what are those rules? If the rules don't cover a Large creature's gear, what house rules create fair costs, weights, and capacities for a Large creature's gear?
From pg. 144 of the Core Rulebook:
and a little further along
Masterwork is an additional flat fee of 300gp, regardless of size.
The damage for large weapons is listed on table 6-5, on pg. 145 of the Core Rulebook.
Table 6-8, on pg. 153 of the Core Rulebook, covers the cost and weight increases for different sizes. For a large creature, the cost and weight would be double.
Masterwork is an additional flat fee of 150gp, regardless of size.
Regarding adventuring equipment:
There is no rule that covers changes for all the different sizes of the items that are available. One of the reasons for this is that among the core races, and those presented in the Advanced Race Guide, none of them are Large. The rules cover Small and Medium sizes because 99% of PCs will be those sizes.
My recommendation would be to follow the rules for weapons and armour. Those are the more important parts of your equipment and the rules are clear regarding large sizes.
As for the rest of the equipment, don't over-complicate things. If an item has a specific ruling regarding its size, weight, or any other aspect, then follow that ruling. Otherwise, simply follow the standard information that is listed for the item. And remember, there is nothing that requires you to have to buy the larger versions of items. I see no reason why you would struggle with a normal sized pouch.
Finally, have a quick chat with your DM about this to clear up any questions you may have and also to make sure that you are both on the same page.