Totally normal.
I have been there, we have al been there.
Right after diagnoses its easy to bounce back and cool with things for a while.. I found things really started hitting me 3 months in.
The best why i have found to deal with this is NOT thinking about it. I learn what i can, i remember it, I apply my carb counting, and other stuff in the most mechanical, scientific way possible - I am a robot in this regard. All without thought.
You can manage well without thinking too much, because if you over think this condition it will eat at you, and bury itself in your chest until its too much to handle and it will hurt. The more you over think it the weaker you will become and its harder to come back then to not start.
Put it out of your head - there is nothing to do but what you are already doing (just make sure you do all you can). No need to think about anything beyond this moment in time.
When you feel sad - Don't think of the past, do not think of the future - focus on this moment right now, not ten minutes from now, or an hour ago. Be happy right now, that is all you have!