i can't have an orgasm

hi, i dont have a really good english so please forgive me if something im writing doesn't make sense or is confusing.ñ

so, im a 21yo woman who don't know how an orgasm is. or thats it's what i think? i simply don't know how, i have been close (i think) but don't know how reach it !! i had the tension in the body that some forums mention and all of that but it just disappears.. i don't know what to do, I'm so frustrated with it i even cry several times to give you an idea. and also when im close i have the reflex of pushing my partner away, although im kinda stopping doing that because i was doing it unconsciously.

I did everything I read on forums and videos, i have a boyfriend who is aware of this and we did some things to help but i simply can't. and it makes me so sad. i cried several times for this.

i come here for help, advice, i don't know, maybe just to vent in a certain way because i don't consider myself capable of having an orgasm (I have only told my partner because he is my first active sexual partner except for my ex who I only been once and it was horrible).

im open to any questions to help this situation so feel free to ask anything you want.