Frustrating

My boyfriend and I have had sex several times now and I still can't orgasm. I really want to but I don't know what we're doing wrong. I know sometimes I don't even try because I don't feel like it and we don't have enough time so I'll just let him finish. Other times he has fingered me or eaten me out and although it feels a little good, it's not the same as masturbating and I don't know what to tell him to make it better. I still enjoy the sex; like it feels good when he's inside me but not orgasm-worthy. Maybe I just take a long time? We're thinking about getting a vibrator to help me or a cock ring so he can last longer but I feel like I shouldn't be having as much of a problem as I am. Maybe I'm not focusing enough? Any suggestions to focus on the feeling so that I don't get in my head? Is he doing something wrong? He's not very experienced either but I don't know how to help him make me cum :/ . We tried some more foreplay but I don't think it was enough for me; it's almost like he doesn't need any at all and I need a ton before we even take our clothes off. I know I posted about this earlier but I tried a couple things and it's still not working; even when I'm horny.