I am 40 and I had to use doctor's help to get pregnant when I wanted even though me and my husband don't have any problem why we could not conceive naturally.
I wonder if I should use birth control and expose my body to extra medicine and side effects and it cost too.

i'm not sure what you are trying to ask. you think that you are infertile therefore think it is not necessary to use birth control because you don't believe that you can conceive without fertility treatment? i suppose you could go without the birth control but you have to be prepared if you find yourself pregnant.