A Story Apropos to Nothing

I sometimes get asked questions like 'how often do you and your husband have sex?' and 'can you really not come without pain?' and 'is it always BDSM-y with the two of you?'
To answer the first question, we try for every night, but that obviously doesn't happen, which isn't to say we're not doing other things which might not be technically called sex, so the whole question gets a little convoluted; to answer the second question, no, I really cannot come without pain; and to answer the third question...it depends on your definition of BDSM.

Since I can't come without pain, I need to get in some S/m if I'm going to orgasm, but the amount varies, depending on the situation. If, for some reason, Husband does not want me come, or does not care if come or not, then that very mentality touches on our D/s power exchange relationship, which would also hit upon elements of our BDSM.
But really, more often than what I think people would believe, a lot of our sex is pretty vanilla-ish; at least, what I consider vanilla-ish. Yes, there is always some nipple pinching involved, some ass slapping, maybe some hip grabbing and 'hold-still'ing, but don't vanilla couples engage in that sort of behavior, too? I mean, how do you have sex without some amount of push/pull, give and take?

So the question is, during the times we're having sex but not making it into a whole "scene," are we being vanilla, or is the simple truth of it is that sex is a power exchange activity, and plenty of vanilla couples make their own little romps and forays into BDSM without realizing it? Where does vanilla end, and kink start?

This story won't answer that question. It's just a funny story.
Last night, Husband and I were enjoying our ritualized 'cuddle/kiss/talk/touch/now-shut-up-and-get-your-mouth-on-my-prick' time, when I accidentally poked him. Let the records show, I state for all to see: it was accidental. 
Did he take it that way? OF COURSE NOT.

He poked me back, which led to a poking joust, which led to me tickling him, which led to him grabbing my panties in the back and pulling them up into a wedgie.
Here is where things went wrong.
He didn't just pull up, along my back; he pulled up, into the sky. It felt like he was lifting me off the bed. It didn't help that he was pulling my panties into my crack so hard, I was launching myself forward just to ease the pressure from my poor womanly parts.
I ended up propelled over the mattress, over him, and straight over the bed, head first.

The first words out of his mouth--I KID YOU NOT--were, "Where did you go?"

For a moment, I lay there over the bed, bent and crumpled, shocked still. Then I exploded.
"What do you mean, 'where did you go?' You pulled me over the bed! I'M RIGHT HERE!"
He bent his face over the side and offered me a hand up. I slapped it away. "Why did you let that happen?" I yelled.
"I didn't let that happen, you pushed yourself off the side," he said very calmly, but I could tell he was trying hard not to burst into laughter.
"But you're supposed to make sure I don't do shit like that," I countered. "It's your job. You're supposed to be in control."
"Yeah, well, I'm human. And you can be unpredictable." I rubbed the back of my head, giving him an accusatory look, and he couldn't hold back anymore; he started laughing until he was red in the face.
"I really hit my head," I said in a small voice. His laughter died down, and he kissed my forehead.
"I'm sorry you hit your head," he said. "Are you okay?"
"No," I pouted. "I hit my head."
"Aw, poor baby. What can I do to make you feel better?"
"Kiss me again."
He kissed me again, and one thing led to another. The sex went on, the fun went on, the bantering-and-countering went on, and the pain in my head went away. Kinda. He distracted me with other pain, which was quite a bit more sharp and deliberate.

I guess, my point of all this is, I can't imagine vanilla sex is free of its accidents and pitfalls, and when that kind of thing happens, I bet vanilla couples handle it very similar to the way we do: by dusting off and keeping the fun going, for as long as possible.