"You're constructing rights as positive, not negative."
As did you when you said "You have a right to ownership in your body...". This is a negative right worded in a positive way. Put in the negative form, it would be worded "No one has a right to ownership in anyone's body but their own". Wording it positively may be less precise, but it is how most people understand it better.
All rights are negative rights, as in "No one has the right to...". If you believe I have stated something incorrectly by phrasing it as a positive, then I apologize.