It would be my belief that regardless of what is in the contract, I own these materials and all the rights to them. I'm sure an over-priced lawyer may beat me in court, but I have my copyright on every webpage.
It would be my belief that you should check the contract, because the university is paying you, and if your contract says what you create is "work for hire," that means the university owns everything you made while they were paying you, regardless of where/when/how you made it. The steps you've taken are no doubt helpful for proving your case, and as a practical matter they're helpful because (like they say) possession is 9/10ths of the law, but you can't just ignore what a contract says. And you certainly can't hope that a court will. It doesn't take an overpriced lawyer to say, "Well, it says here in paragraph 8(a) that everything you created while working for us was work for hire, so buh-bye, it's ours now."
They were developed while I was not working for the school and brought with me and modified slightly. Just checked the contract, and it indicates that I would own it anyway even if they had paid me.
