First relationship, first time: BF is too big for vaginal or anal sex, and I need advice.

Hi everyone, i am 21F n my bf is 24M ​I’ve been with my boyfriend for 7 months. He is my very first boyfriend, and everything regarding sex is completely new to me—I have never even used adult toys. He is incredibly good to me, and we currently have a great oral sex life where we both satisfy each other. ​However, we are struggling with penetration because he is very well-endowed (around 15 cm/6 inches and quite thick). We tried having vaginal sex, but the moment he put just the tip inside, it hurt so bad that I started crying. He immediately stopped and pulled out, which I really appreciated. On top of the physical pain, I realized I have a lot of anxiety about losing my virginity before marriage and a deep fear of getting pregnant. ​Because of that anxiety, I suggested we try anal sex instead. We tried it, but my anus felt way too small, and again, I started crying from the pain, so we had to stop. ​I really want to be able to at least enjoy anal sex with him, but I don't know how to progress. Since I am completely inexperienced, I don't know how to prep my body or overcome the fear and tightness. ​Has anyone else with a well-endowed partner gone through this? ​How can we safely and comfortably transition to anal (or eventually vaginal) sex without it hurting? ​Do I need to start using toys or dilators first to prep myself?