Ladies can I ask something really embarrassing

I’ve been desperate to ask someone but feel really stupid and at least I’m anonymous here.
I’m 24 weeks with my first. I’ve only slept with 1 person and I’m mid 20s so I’ve never had a smear test etc. To be honest I’ve never had anything ‘medical’ happen to me in my life so naturally finding this all very strange and very anxious about it all.
I have always found sex quite painful / uncomfortable and always felt like my partner is too ‘big’ (he’s average it just ‘feels’ that way!). I also find tampons quite painful to use. I went to the doctors about the sex thing when I was at uni as it would cause me to bleed and they just told me to use more lube and sent me away. Nobody has ever actually checked it out. (Boyfriend was also a virgin Til he met me so can’t tell me what’s ‘normal’ or not

)
anyway now I’m really scared that medically I might have something ‘wrong’ down there or I might be quite small/ have an issue and nobody would know about it (until it’s too late and I can’t push a baby out of there!!)
Is it possible to be too small to give birth

(btw I’m not a small person I’m a 5ft7 wide hipped size lady!!)
i am really considering raising this with my midwife and asking her to ‘take a look’ to settle my nerves as I feel like a freak


would that be nuts?!