Under such stress, and emotional turmoil, the grieving process is functioning normally. Even though you aren't doing and going about things how you normally do, this is how your body processes and maintains. I could be wrong, but in my experience I let things flow. It's definitely hard, and people aren't going to understand due to individuality, I would try to just let the grieving happen, take things by the minute or hour, not try and focus on the big day type picture and do your best to do what needs to be done, and take time for your body and brain to relax and go through what it needs to in order to process and get back to health.