I think the use of the present continuous fits well in your sentence.

The situation in your second clause contrasts with that in the previous clause. Moreover, the second clause implies that you see the present routine or situation as temporary. In such cases, it is more idiomatic to use the present continuous. So you should say:

....., but at the moment I'am working at least 10 hours (a day) and some Saturdays.

I think the use of the present continuous fits well in your sentence.

The situation in your second clause contrasts with that in the previous clause. Moreover, the second clause implies that you see the present routine or situation as temporary. In such cases, it is more idiomatic to use the present continuous. So you should say:

....., but at the moment I'am working at least 10 hours (a day) and some Saturdays.

You can also use the present simple if you see this change as permanent.

I think the use of the present continuous fits well in your sentence.

Your second clause contrasts with the previous clause. Moreover, the second clause implies that you see the present routine or situation as temprary. In such cases, it is more idiomatic to use the present continuous. So you should say:

....., but at the moment I'am working at least 10 hours (a day) and some Saturdays.

I think the use of the present continuous fits well in your sentence.

The situation in your second clause contrasts with that in the previous clause. Moreover, the second clause implies that you see the present routine or situation as temporary. In such cases, it is more idiomatic to use the present continuous. So you should say:

....., but at the moment I'am working at least 10 hours (a day) and some Saturdays.