Adding spermicide to birth control pill

Hello all!!! So basically, I have started to become sexually active within the past 6 months or so. I’m on the pill, and I’m very good about taking it at the same time every day. Over the past couple weeks, me and boyfriend have decided that it was okay for him to finish inside me. While I know the pill is around 99% effective, it would make me feel better to try and increase those chances of not getting pregnant if I could. I was looking into it, and saw there was something called spermicide films that you insert inside yourself before you have sex, and it’s supposed to kill sperm cells. I was wondering if any of you use this is conjunction with your birth control, and has it been successful? Or just in general, what are your thoughts on this? Thank you so much in advance!