I used to have mensuration cycles of 28-30 days normally

Patient: I used to have mensuration cycles of 28-30 days normally. According to my normal cycle, My periods may come on 6th or 7th of June. I am going to meet my fiance from 29th may to 6th June. We want to have sex without condoms. I don’t want to be pregnant at any cost. Please suggest me the dates(if any), in which we can have sex without condoms and not get pregnant even if he ejaculates inside me. Doctor, we don’t have any problem in having sex even on first day of my periods. So, kindly suggest me the dates according to my cycles if any. One thing more, I don’t want to take any pills like i-pill or unwanted 72. In those circumstances, its better for us to use condoms. Please help me out doctor. Thanks in advance.

Doctor: