I would try meditation and some yoga sounds like you need to let loose. Also have some candles music when you have sex. It sounds mental even though they said it isn't. Also different sex toys can help.
girl , you're 20... your sexual partners up until now have been teenage boys just figuring out their way around a vagina... you're alright, if its not any meds you're taking its probably the fact that you're still young and haven't really figured out what makes you tick
Aww I'm sorry this is happening, and it's stressing you out so much.
A few things come to mind.
Are you on any meds? Antidepressants are known for causing sexual side effects, for example, and can make orgasms really difficult. Other meds can, too, like birth control, but anti-depressants are probably at the top of the list.
This doesn't exactly describe you, but may be a place to start. This describes people who know they are orgasming, but can't feel pleasure from it. I'm not sure you can feel the orgasm, is that correct?
It could be psychological, but since you have the same issue when you are by yourself, or when using a vibe, that seems less psychological than physical to me, but you're better to answer that question than I am.
This talks about different reasons why, but also mentions blood flow to the clitoris - https://health.clevelandclinic.org/theres-help-for-women-who-cant-achieve-orgasm/
You're also only 20 (and I don't mean that in any kind of condescending way). I was having sex for a few years before I had my first orgasm. Some women can't have orgasms from sex alone - many, in fact - https://abcnews.go.com/Health/ReproductiveHealth/sex-study-female-orgasm-eludes-majority-women/story?id=8485289, and need clitoral stimulation, some women need different sensations from a vibe, so maybe the vibe you used wasn't the one for you. Some women like direct pressure on the clitoris, others like it just to the side.
So first, my suggestion would be to review any meds you're on. Then, talk to your doctor or find a good GYN who is comfortable talking about sex, and go from there. You've already got a head start with a partner who is comfortable talking about it. :)