Teen Sex?

Hi Everyone! I hope you're all having a good day/night. I need everyone's opinion, please, me and my boyfriend will be dating for 2 years this month. We're both sophomores, he's 16 and I turn 16 in July. A little more background, we met in 6th grade and became best friends and started dating the end of 8th grade year. We both want to start having sex and his mom is cool with it, but my mom makes it virtually impossible for me to talk about it with her, she makes it so uncomfortable that I just don't wanna bring it up, but I don't want to do it behind her back. She refuses to let me get on birth control and I don't know what else to do because I care and I want her to know but she makes it crazy frustrating.. Do y'all have any ideas/suggestions to what I can say or do? I can buy my own condoms and Plan B.