Is it normal to have rough sex all the time?

STOP the self hate. Just stop. Take a breath.
You have, from the sounds of it, a personality/sexuality axis where you are dominate and able to play harder than most. And you're feeling guilty. That guilt will undo you.

Double-check your toys, your tools, and your methods. Accept yourself and your desires to prevent a feedback loop on yourself. If you double-bind your guilt and self-loathing with your physicality then when she invites you in to your desire, and provides herself for the transgression, you will grow to hate her for enabling your "sick"

What if you do indeed get off on hurting her? Then it's up to you to do your best with the hand you've been dealt. Of meeting in the middle in the catering of the desires. Master yourself and your desire. Get your sexuality to serve you.

And love her because at the moment it sounds like you two match up. Open up more communication after your soul searching. Be strong. Know what you want. And find a path where you'll stop hurting yourself.

Just talk to her about how you feel. Then you'll have your answer.

If she's generally honest with you about her feelings then she probably would have spoken up by now of she didn't like it, but you never know. Sometimes we put up with things that we don't like because we don't want to let our partner down.

death by bdsm

Normal, but be careful! Especially with the choking part. Also, try bondage if you haven't already, its fucking awesome.