It is not an issue of you doing something wrong. She could be misinterpreting the signals you are sending. It appears that the two of you want a committed relationship and you've mentioned wanting a long term relationship. Since you have neither engaged or made more specific plans only after 6 months (which is wise and it does make sense) you do have a right to privacy and some kind of freedom (that includes not jumping to hasty decisions and having her things in the apartment)
What you are doing is wise to take things at a normal pace. Six months is really not such a long time dating someone. You are also divorced and caution on your part is only a healthy response.