As alwaysconfused says, when you first stop taking the pill, it isn't really a proper period you have, just a withdrawl bleed. It can take your body several months to readjust and settle being 'back to normal'. Some women can conceive straight away, others take months, even years - there's nothing wrong, just the timing isn't right. to get pregnant the most fertile time is roughly half way through your cycle, that is two weeks after you finished your last period, or two weeks before your next one is due. It would be a good idea for you both to stop smoking, not just the fertility aspect but your general health and that of your future child.
Your boyfriend shouldn't wear tight underwear or jeans as it's important to keep the testicles cool for healthy sperm. don't worry if you don't get pregnant straight away, time is on your side.