Golden Week

I'm not a morning person so I prefer to work after 11 p.m..
I can't start my day without coffee and have more than 3 coffees a day. Is it too much? Hope not!
The Golden Week is a collection of four national holidays and it's coming soon. I'm so excited that I've already told my friends what day I'm coming back to my hometown.
I miss my grandmother so much so I'm buying a lot of gifts for her. I hope she is well.

I just can't wait to go back:-)

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Very good! I only have one correction...

I can't start my day without coffee and have more than 3 coffees a day.

When you are constructing your sentence this way, your meaning is unclear. The word "can't" can apply to both the words "start" and "have".  Of course the problem with that is that now you are saying,

"I can't start my day...." and "I can't have more than...." 

I don't believe this is your intention.

Better to be clear.

"I can't start my day without coffee, and I usually have more than 3 coffees a day.

I hope that helps! Jerry