I was also 小產 last month, and was nearly 5 months pregnant(more than you). I can understand what you feel actually. Like you, I cried and cried many many times, and I believe I caused 產後抑鬱. I couldn't face on colleagues and relatives. Also, I wanted to have bb again soonest as possible.
But, do you know why you're miscarriage ? It's because the bb had problems, that it had to go naturally. It's good to you and your bb.
Now, what is important to you is to get healthier.
A healthy mother will have a healthy baby.
Don't hurry yourself to have pregnant very soon, otherwise, bad luck will come again
I understand it's a difficult moment to you now. But as time goes by, you will be better and then plan for a healthy bb.
About your 奶奶, I think you had better not see her in the near future till you recover.