It's not you OP, my person in my life like this is my sister! I know EXACTLY what you mean and it baffles the shit out of me too if I'm being honest, I think some people on here don't really understand because they don't know one personally.
With most people I have this back and forth sparring type conversational style, I find it pretty effortless, I listen more to the talky ones and talk more on the listeny ones, but with her I really struggle at times, I end up having to ask questions because normal conversation style talking doesn't really work, she tends to answer in 'closed off' replies which don't lead to any further topics..
How's so and so (her DH, kids, pets etc)?
"They're fine" ..
big pause...
Did you see that thing on TV last night?
"no didn't see it" ..
Have you got any plans for your birthday (upcoming)?
"not really" ..
There is ample opportunity if she doesn't want to talk about herself to ask me about my life, current events, news, politics, music, films, hobbies, DH, kids, pets, job, holidays, there's nothing I wouldn't have a conversation about.. but she doesn't ask a single thing, it seems to the casual observer that she just isn't interested..
So I'll sometimes say something like 'one of the kids is having a difficult time with something" and she will not engage in it, she'll answer quite dismissively like, "I'm sure they'll grow out of it eventually" etc.
I did an experiment a little while back, she wanted to pop round to see me, so I decided to let her do the talking.. and she just didn't talk, I shit you not we sat in virtual silence for an hour.. not once did she ask me a singles question to get the ball rolling on a conversation.. not once!! I had to give in eventually as the cringe became too great.. I still don't understand it, I just accept it now, but I often feel exhausted after she's gone.
So all those people saying 'you talk to much' 'you bombard with questions' .. it's not necessarily that, it's just hard having one way conversations all the time and having to carry the load.