Could you try something like this for a week or two?
Have eggs and bacon for breakkie or greek yoghurt (full fat) with a few berries or dry-roasted almond splits?
Have salad at lunch - include a good source of protein like tuna, meat. Stick to lettuce, green pepper, cucumber, half a tomato, perhaps a bit of onion. Add a bit of cheese or an oil/vinegar dressing.
Have Veg and meat/fish/egg for dinner.
For snacks, try a small amount of almonds (10 or so), bite sized cheeses, salami sticks, raw veg like cucumber, peppers, carrots if you tolerate them.
If you feel hungry, eat a bit more protein than you perhaps do (unless you have kidney problems or something else preventing it). If you do strength exercise, try a bit of protein afterwards instead of (perhaps) carb snacks - it will help your muscles more as the body can convert a certain bit of it to glucose, but a lot slower. Of course do this only when you are not super low after exercise.
Don't be too scared of fat. In the insulin/sugar equation, fat doesn't really have an effect, it is not often fat that makes you fat, but rather the excess insulin used to cope with sugars, which then stores the sugar if it isn't used.
Be a bit careful with your insulin for a bit while you adjust further - keep an eye on blood sugar until you know if you go low/adjust dose down.
Use common sense while adjusting so you stay safe, but I think the fruit, cereal and cereal bars are the main problems for you - my lowest cereal bar I have found has been 15g carb on it's own, cereal is high in carb and fruit has fructose (carb).
I have gone down to about 30-40g carb per day on insulin - it takes a little bit of tampering and perhaps a slower start (which it sounds like you have also done for a while).
Besides, you may want to also consult a measuring tape - muscles are more dense than fat, so you might find a toning effect taking place which would explain at least some of the standstill. Waist, thighs, upper arms etc measurements once a week might keep you more motivated if this is the case.
Good Luck.