I’m busy wasting my time

I think this is the "don't break the chain" concept. I attempted this, this month and am in the same conceptual spot the OP is. I have set some goals and was tracking on a calendar if I did the thing that day. The calendar is mostly blank since I stopped tracking it. Its a pen/paper calendar since digital tracking doesn't work for me and puts something in my hands that distracts me from the goals!

I feel like restricting access to sites isn't the way. I'm in a spot where we need to let our kids have more technology freedoms since in a couple years they could be off to college and there isn't going to be someone asking them to leave their phone/tablet/gaming device with them or limiting their time.

I need to reset and build some constructive habits and discipline.

Well, there's nothing said about controlling your kids, that's a different dilemma, but on an individual level, restricting websites for just yourself is the best way to go. It could be something like putting your phone in a timed lockbox for a few hours, or not buying cookies for the house so you don't randomly eat, or using the premium website blockers that can't be uninstalled. Every bit of media is carefully designed by the brightest minds to give you a small dopamine hit so you keep coming back. The best discipline is not needing to use your discipline. I'm on you with the habits, we live lives unconsciously most of the time so habits are absolutely crucial to ensuring we don't randomly end up scrolling Facebook for 3 hours and then wondering where the day went.