HEELPPPPP

Missed two or three pills from 24-26th decemember. Then I continued taking them as normal, from the 27th till today. On the 4th January my boyfriend and I had unprotected sex but the next day got the morning after pill, just to be safe, but will it be effective? One woman at a pharmacy said not to take the pill as it won't be effective and to go to my gp and take something stronger, at this point I was crying and in a state as that's not what I expected and my boyfriend rang the NHS 111 and they said to go to another pharmacy and get the pill as there's no reason why it shouldn't, so we went and got the pill from another place very easily. Can you explain why the first pharmacist said it wouldn't be effective? And if it is effective, how will I know it's worked asap?