Cant orgasm

I'm 22, been sexually active since I was 19 I found my amazing partner 2 years ago, I know what an orgasm feels like, I no the stages I go though before I orgasm but most of the time hes on top /have sex ( in any position), I get to the last stage before I orgasm (my eyes go twitching starts, the feeling is there and i my face changes but I can seem to go through into orgasm

99% of the time we have great eye watering sex

Is anyone the same or can give me any tips and tricks to