Unable to orgasm with partner

I've been with my bf for 5 months now, and he's the first sexual partner I've had (I am his first, as well). I'm very much a late bloomer when it comes to sex, but am no stranger to masturbation.

I have a fairly high sex drive and when I'm alone, I'm able to get off quite easily, either with my hand or a vibrator. Orgasms have always come pretty easily to me, and I usually end up having multiple orgasms each session. I orgasm most easily on my stomach with my legs and arms tensed, though I can do so on my back quite easily, as well, but seem to require my abdominal muscles to also be tensed along with my arms and legs, which I'm sure doesn't look all that flattering.

I've definitely gotten very close to orgasming with my bf, but have not been able to get over that crest, for lack of a better term. The times I've gotten closest have been during PIV with him on top and thrusting hard and steady and me on top, also thrusting hard and steady. I've also gotten close when he's gone down on me (something I wish he would do more).

I think I'm most likely to orgasm from him going down on me, but the few times he has, he's done it for about 10 - 15 min before getting too tired, which just left me frustrated. Because of this, when he does go down on me, all I can think about is the fact that I'm taking to long, he's getting tired/bored, etc.

During PIV, he comes pretty easily when thrusting hard, so that does not leave me the time necessary to orgasm.

Him using his hands on me has yet to do all that much, and he quickly will complain about his hand getting tired, which, once again, makes me constantly think I'm taking too long, and he's getting tired.

I've used my vibrator while with him several times, usually with him kissing/stroking me, and even then, I've only been able to orgasm once, and that was after a long time (30+ min) and a ton of effort/concentration. This is never an issue when I'm alone, and can easily orgasm in less than 10 min.

I know having an orgasm isn't everything, but I'm becoming super frustrated at this point. Any advice would be deeply appreciated.