When does a girl know that she likes being tied up?

I've been thinking about this for a while now. I can't remember what triggered my thoughts on this, I think it might have been a porn clip that was very rough with a final interview with the girl.

I have mentioned before that I started masturbating when I was little, I think I was 5 or so. I remember a slightly older child showing me how (not as bad as it sounds... I didn't see an inch of skin and she didn't touch me). From that age on I explored sexuality as a child, I delved into images and ideas that turned me on and some were odd of course, as a child sex is completely different. I barely knew where the penis went, but I did know that boys were involved.

I'm not entirely sure when it started or when I figured it out, but I would get myself into tight spots, wrapping my legs and thighs with tight things. I would quickly reach orgasm that way. I used this technique quite often for years, up until I was a pre-teen. Who am I kidding. I still use it lol.

I remember using my pjs, getting both my legs into one leg of my pjs like a long, very tight skirt. Not something I do anymore mind you lol, but I do use tight clothing, things that I can feel hinder movement, especially in my thighs. Tight skirts, tight shorts even.

Maybe it comes from knowing I shouldn't have been doing it and the constriction was me holding myself back from it... except it just turned me on more.

I would also do the opposite of constriction. I would force my legs apart even if I wanted them bound together. I would spread my legs as wide as I could and keep them there until I came. Another technique I still use on occasion. 

Wanting to be tied up is just a natural evolution of these fantasies. Hand tying is something that I haven't been able to explore and it's harder too. For one, I can't do it on my own. Secondly if I want to get off I need at least one hand free.
I've only had my hands tied up once and it didn't really count. I could have gotten out of it too easily. I was tied to a post on my bed. I think if I were to ask to be tied up I'd simply ask for my hands to be tied behind my back, I'd even try my arms being tied above my elbows. But to go along with that I'd love my legs to be tied at the ankles and just above the knees.

Then bent over the back of a couch kneeling and getting fucked from behind or laying on my back, legs pushed up over my head.... either way works for me.

It took me forever to find a decent photograph of the type of tying I'd like to try. This is the best image I could find and it still doesn't reflect exactly what I'd like. The arms should be tied just above the elbows, tightly together, just the arms, it forces the shoulders back and chest out. It looks good and I imagine it's rather uncomfortable.