I am getting confused with the tense, hope someone can help me deal with it...
Can someone tell if my answer are possible or why they are wrong?

1.

Mine:
I was tired yesterday because I did not slept well the night before.

Correct one:
I was tired yesterday because I had not slept well the night before.

2.
Mine:
When I left the house this morning,it had already been raining.

Correct:
When I left the house this morning,it was already raining.

3.
Mine:
I do not wear my watch because it is being fixed.
Correct:

I am not wearing my watch because it is being fixed.

4.
Mine:
Nothing much had happened when I got to the meeting.

Correct:
Nothing much was happening when I got to the meeting.

1.
Mine:
I was tired yesterday because I did not slept well the night before. ☑️

Correct one:
I was tired yesterday because I had not slept well the night before.☑️

Best option:
I was tired yesterday, due to not sleeping well the night before. ☑️☑️

2.
Mine:
When I left the house this morning,it had already been raining. [[Maybe]]

Correct:
When I left the house this morning,it was already raining.☑️

Best option:
It was raining when left the house this morning. ☑️☑️

3.
Mine:
I do not wear my watch because it is being fixed.❌

Correct:
I am not wearing my watch because it is being fixed.☑️☑️
^^ use ‘I’m not’ is better

4.
Mine:
Nothing much had happened when I got to the meeting.❌

You could say:
Prior to my arrival, Nothing much had happened in the meeting☑️☑️

Correct:
Nothing much was happening when I got to the meeting.☑️☑️