Not sure if this is the right place to ask, so, please move if not

I have been on the mini pill for about 5 weeks, and get headaches, nausa & dizzy spells, and my fingers get bloated type feelings. I am not sure if its related, but, a friend mentioned that she had similar experiences when on the mini pill. I received no little info sheet when i got the pill, so i am not sure.

Also, i have not yet got AF, and havent physically b/f Aiden since he was about 7weeks. I expressed till he was 10weeks, and formula since then. Is the mini pill preventing me from getting AF?

Is it still possible to fall preg while on the mini pill?