Hi, welcome to HCm, I am Dr. Das
First of all, as the time during sexual contact is near the expected date of period, it is theoretically impossible to get pregnant (provided you have a regular period of 28 days cycle.
Secondly, As you have taken Primolut N
it also prevents any possible pregnancy
Thirdly, if in rare case you get pregnant, then there is very much updated medicine which can be taken if you dont want pregnancy.
So, dont worry.