Is Unprotected Sex Safe Post 21 Day Course Of Birth Control Pills?

hello doctor, my gynec suggested me to use femilon as contraceptive. my age is 24 and weight is 49. recently i am having delays in periods, like 34/35 day cycle instead of 28/30 day that i had. until now we have used only condoms and this is the first time I will be taking pills.my question is, after completing the 21 day course, can I still continue to have unprotected sex with my partner until my next period starts... because if my cycle is ~34 days, post 21 pills is it safe to have unprotected sex? i am meeting my parner only on the 20th day of my cycle for a week. so out of my 7 days of intimacy with him, my pills will last only for first two days.looking forward for your valuable guidance. Thanks!