Eventually as a type 1, you can have potato chips if you want. But what is happening now is you probably are making some kind of insulin still, you won't make any at some point, but the trick is finding how much insulin you need right now and the fact that might change slowly or rapidly.
So it's a little bit of a trick, but once you learn it, it becomes pretty easy. I eat potato chips if I want to, I just dose my insulin appropriately for it.
300-400 is too high, but they start you off in low doses until they figure out what works. They don't want you to go too low, which is dangerous. So they go slowly. You can usually call them with numbers like that and they probably will tell you an adjustment. But make sure you are also testing plenty to get your patterns for them.