My work

Today I woke up early to work.
I had many tasks.
However it is not a surprise, because as I'm an accountant, the jobs are never little few. (For this correction I assume you mean there is a lot of work, which is why I changed the word to few).
But I like the profession and I'm happy and proud with  of my choice. (I see why you got confused.  You would say "happy with my choice" or "proud of my choice".  Since you combined happy and proud, you use of because it comes after proud.)

My Work

Today I woke up early to work.
I had many tasks to finish/accomplish. 
However, it is not surprising/no surprise, because as I'm an accountant, so the jobs tasks are never little trivial/unimportant.
But  However, I like this profession and. I'm happy and proud with my choice.

My work

Today I woke up early to work. (or ...to go to work.)
I had many tasks to do.
However, it is not a surprise. Since  I'm an accountant, the jobs are never little. (small would probably be a better word.)
But, I like the profession and I'm happy and proud with my choice.