Well, congrats on getting a correct diagnosis. The bad news is that you'll now be on insulin for life. The good news is that you're not T2 and insulin resistant, so you don't need to follow the extreme low-carb diet that many T2s do. (Some T1s do go very low carb, because they find their blood sugars easier to manage with less carbohydrate and insulin on board, but many don't.)
Most of the dietary advice you've had so far is for T2s, as that was your original diagnosis. As a T1 you'll have more freedom to match your insulin to your food!