I'm sleepy.

I am so sleepy, but I am trying to commit to writing one notebook entry here everyday.

Your sentence is well constructed, but there is a gap between your two clauses. There is an implied connection between the two statements, but it is not really connected correctly. The use of 'but' implies an action that you will not do until you write, but what you have written before is just a feeling. 

As you say 'I am trying to commit', it is ambiguous to me, whether or not you have made this commitment. It literally means that you are still contemplating making such a commitment. To me it seems that you are not firm in this commitment, maybe you keep it some days and not on other days. Staying awake to write something will help to meet this commitment at least for today. Is this correct? 

If you have been successful in writing every day, i would say this 'I want to go to sleep, but I also want to keep my commitment to write one Notebook entry here each day' It is directly implied that keeping the commitment is the reason for not sleeping. It also directly states that the commitment has been made, and kept thus far.

These are just some thoughts, I think your English is great, hopefully it will be helpful for you to have this feedback on the fine detail of what you have written!

I hope you had a good sleep!

I'm sleepy

I am so sleepy, but I am trying to commit to writing one notebook entry here everyday.

I do not want to spill my personal information or write my feelings here and let strangers read it. Ha!
I am sharing my other thoughts instead.

So here it goes. . .

It's 1:30 am here in my country. I'm living in a dormitory and I'm the only one awake right now, it seems.
I think I should really go to sleep.

...

Good night!