I'm sorry to hear that! I was diagnosed about 3 years ago and have found that dining at Disney is easier than dining out at home. Someone else already mention Erin McKenna's Bakery in Disney Springs, and I agree that it's a must. The last time I stayed at Animal Kingdom Lodge, the Mara had mini brownie cupcakes available in the refrigerated case. There were 6 (I think) per package with different flavors of icing. The full-size ones from the bakery in Disney Springs are great, too.
Make sure you note your dietary restriction on your reservations - "Gluten/Wheat" will be one of the options available under Food Allergies. If you already have reservations made without that noted, just let the restaurant staff know about it when you arrive and they'll be able to help you. Do know that some of the restaurants not owned by Disney may not be able to accommodate you as safely as Disney's restaurants can, but I had a good experience at Blaze in Disney Springs (just ask for fresh sauce, cheese, etc. to avoid cross-contamination).
A lot of the family-style meals will bring you your own platter (albeit smaller than the one the rest of your group will share). If you stay at Poly, you can even get an in-room feast that is the same meal you get at Ohana without the stress of trying to get a reservation. When you call, just request the gluten-free version and they'll bring it with white rice instead of noodles and the glaze on the meat will be gluten-free as well.
The only buffet I've had since being diagnosed has been breakfast at Boma, and I can say that they will take great care of you there. The only thing I get directly from the buffet line is an omelet. I recommend doing that at any breakfast buffet instead of the scrambled eggs on the buffet line to avoid potential cross-contamination from other guests who aren't aware that they could be causing problems for the rest of us (plus fresh eggs cooked to order beat watery chafing dish eggs any day no matter where you're dining). Everything else I get is brought to me from the kitchen, but mainly I get the waffles and a donut (they have Kinnikinnick donuts that I really enjoy). If you're not sure of anything, you can ask for a chef to come to your table to go over your needs.
Many restaurants have a separate kitchen for allergy orders while others will have a manager prepare the food to ensure it is safe, so there is sometimes a longer wait for your food at the Quick Service restaurants compared to everyone else but the wait isn't always longer. There have even been a few times where my food came out before my wife's, but generally your will take a little longer. Sometimes we compensate for this by having me order first. Unfortunately, mobile ordering doesn't always list the allergy-friendly options so ordering ahead hasn't been an option for us other than lunch at Be Our Guest.
The Halloween Party options were a little different this year than the last time we went. They used to just have snack-size bags of Enjoy Life chocolate chip cookies at various locations along the trick-or-treat map. This year, they just gave out tokens that you then brought back to the Town Square Theater to redeem for treats, which took longer but did allow them to offer more options than just the cookies. The only Party-exclusive snack I tried this year was the Sally cake pop, which was made with gluten-free cake but was more icing than cake. I know they also offered worms and dirt with gluten-free cake, but I haven't had that yet. Unfortunately, the snack options are usually limited for me. I haven't been to the Christmas Party in a few years, but they also were giving out the Enjoy Life cookies the last time we were there.
