Hi Midori,
the foods you mention are sensible. Oat cakes are great and you're right, you're looking for brown carbs. Basically be suspicious of anything yellow or white (white bread, white rice, chips, mashed potato, batter, pastry etc). Wholegrain carbs are better for you but you'll need to test your blood sugar and adjust portion sizes. I used to be able to have 75g dry weight of brown rice or brown pasta but in the last week or so (since 36 wks) have had to drop it to 60g. It's normal for sugar control to get harder the longer you go on.
Cooked meat and eggs are great and fish and cheese, all protein. Fat lowers sugar absorption in your blood. Watch out for the yogurt, some "lite" ones are low in fat and high in sugar, you want the opposite. Wholenut peanut butter is fine, but not the smooth or sweetened stuff.
Muesli gives me very high blood sugar, I think because of the dried fruit and I buy the unsweetened version. The only breakfasts I get away with are wholenut peanut butter on granary toast, scrambled egg on granary toast or fried eggs and bacon.
Fruit is great, but you need the fibre to slow digestion of the fructose so it needs to be whole raw fruits. Cooked or pureed (like in a smoothie) aren't likely to be okay. I can get away with strawberries and cream for pudding. Dark chocolate is fine and my mum makes a cake with dark chocolate, ground almonds and very little sugar and that's okay so long as I have a small piece.
I'm finding cooked veg a problem. Vegetable curry is my nemesis! I think its cooking the veg for so long makes it too easy to digest. The same curry with meat in it is okay. Do watch the sugar content of cooking sauces - Chinese ones tend to be very sweet.
Cheese is a great snack and cheese on granary toast makes a good lunch. Adding cheese to anything will lower the amount your blood sugar increases. So mashed potatoes are a disaster area but if you do half white potatoes half sweet potatoes (I know it sounds bizarre but they are low GI) and grate in lots of cheese you'll probably be okay.
So sorry to hear you have other complications too. I do as well - all immune related. I'm being induced on 4th April so will try every trick in the book to get baby to come early before then (pineapple eating aside)!!
Do let me know if you would like more suggestions.