I can relate so much to your post -- I had all those gross symptoms too. In the beginning cutting gluten I've found it's hard to differentiate between possible cross contamination, other food intolerances (dairy, soy, corn, nightshades, coffee, etc) & just general healing. It wasn't until I cut gluten completely that I realized I had other food intolerances, which I was mistaking for gluten reactions. Lactose intolerance is common for celiacs, for instance. If you still eat dairy you could try cut it for 2 weeks then add it back in & see if you react. If you react to it, there's the chance you could tolerate dairy later on, once you're healed from being gluten-free.
For the first 8 months of me being "gluten free", I was still eating a lot of packaged "gluten free" foods, but I've since found instead of switching to all gluten-free versions of foods (some of which are made in a wheat-processing-facility), it's best to stick to whole foods. After being sick with gluten for so long it's important we're eating as much good food as we can -- usually means avoiding packaged stuff, even the 'gluten free packages'. Luckily, meat, eggs, fish, fruit & veg are all naturally gluten free & safe
Making your own sauces is the way to go. I've been infusing bottles of olive oil with herbs &/or garlic cloves for extra flavour. Stock up on safe spices: McCormick brand (glass bottle with the green label) is gluten-free.
Cooking in batches is a good idea too; freeze individual meals in ziplocks.
Choices sells a lot of gluten-free (safe) things & they have a rice bakery that does only gluten-free baking. They have ridiculously good "sourdough" rolls! Enjoy Life & Glutino are safe brands for snacks too. Silverhills makes two great gluten-free bread (the best I've tried), "Chia Chia" & "Mack's Flax". They are usually in the frozen section of SaveOnFoods or at Planet Organic. Make sure you get the gluten-free version though, as they also make regular bread with identical names.
If you're going to buy packaged, look for the gluten-free in a circle label; that means it's certified safe. Some products say 'gluten free' (as in no gluten ingredients added), but if they're made in a wheat facility, they're not safe for the super-sensitive.
A great source for certified gluten-free nuts/dried fruit/choc/candy/treats/baking goods is: nuts .com; they sell bulk & ship to Canada. Nuts & trailmix (you can buy bulk ingredients & mix your own are easy grab&go snacks. Did I mention they're CERTIFIED gluten-free?! (Just make sure you're shopping in the gluten-free section only; they also sell reg stuff).
If you do any baking (or are willing to try), google Elana's Pantry; she has lots of really simple easy recipes (bread/muffins/desserts inc. meal ideas). I am not the baking type but her recipes are great & pretty much foolproof. Best of all, most recipes use the same base ingredients so you don't have to buy lots of different items!
I found going "paleo" at first helped immensely. I've been eating this way for a month now & my symptoms are finally fading. My gluten-free diet was not enough. Elimination diets or restricted diets (like paleo) are an option to look into if a gluten-free isn't helping. Also, a full-spectrum multivitamin, digestive enzymes & probiotics are helpful to take in the beginning to support your digestion.
Otherwise, for cross contamination, make sure you have your own toaster, set of wooden spoons, teflon dishes, scratched cutting boards, colander.. all of those items can 'hide' gluten.
Hope some of this helps