So this probably isn’t what you want to hear but, you should see a doctor about this.
Rarely a hymen can be ‘septate’ which means instead of it just being a fringe around the inside of your vagina it actually blocks it a bit, or it can even be completely blocking it (imperforate). Or some mix in between:
It’s a really easy fix but needs to be done by a doctor, so I know it can be embarrassing but you’ve been brave enough to write to me, so I really encourage you to just talk to them about it, and get this sorted.
Even if it isn’t that, it’s some kind of issue that it’s worth getting medical advice on. I know even in western countries it’s hard and in other cultures even more difficult but you are more than your culture and you need to be confident taking responsibility for your sexual health, rather than just being scared to talk about it and so suffering silently, don’t do that!
And of course you don’t need to say ‘I keep trying to fuck myself and it won’t happen’ – your best bet is using tampons as the excuse ‘They just won’t go in and it hurts’. And ask for a female doctor, most places will respect that.
I hope that helps! Get it sorted and start to enjoy penetration, it’s literally what your pussy is for!