Yes I can get a fist in me up to nearly the elbow! Well, only my man I'll allow to get in that far and it takes time but I'm definitely very long inside! I'm surprised it doesn't come out of my mouth!!! 

I've been told mine is long as well, I also have a really tilted cervix which makes having smears/exams/coil change a nightmare! I can take a big cock as well lol

In my time I have had big cocks, thick cocks, and very small ones and all the rest in  between. 
I often found that the doggy position hurt and i felt like my insides were being pushed to the limit making it extremely painful.
It was my least favourite position, which of course was an occupational hazard as so many men like to finish this way   
At other times even if the cock was big it felt nice.  I too have an odd shaped cervix and think that could have had a lot to do with it

 I have a tilted cervix so they have a bit of trouble with smears. 

Length-wise is no problem but I cannot take girth. A large cock just will not even go in without causing pain. It hurts at that rough bit just inside (no idea if it even has a name). Thankfully, I rarely get guys that big but I have had to refuse penetration before.

Bizarrely,  I can take a wider cock anally.

This is so funny, I didn't even know this was a thing!

I wonder what dna gene determines this lol