To tag on a relevant other point, I’ll mention that many people find the stimulation of the outside of the vagina and inside walls to be the pleasurable part rather than the “poking” of the back aka top of the vagina. If it’s just the back of your vagina, e.g the cervix, that hurts to be poked, that is normal. Sexual stimulation makes the vagina expand in size, accommodating the insertion of a penis; sex¹ should be gently inserted unless you’ve requested otherwise, being one of the lesser number of receivers who enjoy rough sex - it’s courtesy. It may be the case that your vagina is particularly short and hence you’ve already noticed the discomfort of insertions.

¹ also an archaic term for a penis lol, used as such here.