Joh It is interesting to read why you have now a chastity contract and what your goal is. But I do not see exactly where you want to go with it.
I understand the different exception not wearing it but I can't follow why you wear it loose. I think if no exception apply you should wear it well fitted.
Think of it like wearing a wedding ring. A wedding ring does not prevent you from doing anything. It's a symbol. An announcement that you are in a serious relationship.
Part of the reason I want to do it is just to show my partner I take the relationship seriously, that I'm willing to undergo the inconvenience to show some fidelity. Also, I'd really like to understand better what people who wear belts experience. Also, I'd like to see if using the belt adds something to the relationship.
I wear it loose because the belt is more symbolic than anything. I am not going to have sex with someone else and I don't need a belt to prevent that. I have not sworn off masturbation so I don't need it for that. I will only masturbate with my partner in mind. I can control that without a belt. I simply won't do it otherwise.