You should be calling your physician for factual information pertaining to you and to ask these questions...
As for just starting using "the pill"... Till you have been "on the pill" for a entire package worth you are not fully protected and yes indeed you can get pregnant.
This should of been explained to you clearly when you took the advice of your doctor about starting this regimen of protection.
be using another form of B/C or run the risk of becoming pregnant at this time.
Nothing is foolproof but abstinence too...
get pregnant while on the pill...it happens.
Certain medications also reduce the ability of the pill to work most effectively.
In the packaging is a leaflet with every pack of pills, included by law from the manufacturer...read it.
It is important you know what you are taking, the side effects, what is common and what is not and when you should be seeking emergent medical care for certain reactions.
When you picked up your prescription you should of been asked by the pharmacy staff if you understood or had any questions...
Go speak to the pharmacist...they are a wealth of information they can share.
You should be seeking out your information from your doctor though not from unknown strangers...sorry.