Without any context, it’s now.  

I am reading this text.

I am looking at the screen.

I am thinking about my next holiday.

This action is happening now. Perhaps it started in the past and will finish in the future but that is not expressed.

Context

I’m watching a great series at the moment.

I’m working at home this week.

I’m writing a book.

This action may or may not be happening right now. It is happening around the present.  It is for a temporary time.  It is not in general.

We need to pay attention to context.

I’m always +ing

What do you do in the morning?

I brush my teeth.

I have a coffee.

We can use always to emphasise this.

I always brush my teeth.

BUT

If we say

I’m always brushing my teeth

this means “I do this and it is too much”

He’s always smoking

They are always playing loud music

She’s always watching TV.