I have been feeling like something is breathing in my tommy I actually feel like that every time I am pregnant when does a fetus start breathing?

A fetus starts breathing when it's born.

It isn't until later in the pregnancy that it starts working out its lungs as well.

Your innards around going to be moving and shifting to allow for the growing babe. It is probably that sensation that your brain is interpreting as breathing. Your brain does weird things. This is probably just a quirk of yours.