Advice For Building A New Routine?

I have a bit of a weird life in that I almost never leave the house and I only have one solid time anchor every day. I'm part self-employed part stay at home wife, which means I rarely have deadlines and honestly I usually have to look up what date it is because I don't really have to keep track. I'm one of those people that tends to work best when I can just put on background noise and loose myself in a project. It's pretty common for me to sit and work on something for 4 hours without realizing how much time has passed. After a lot of trial and error, I figured out a routine where I would assign all of my big projects to a specific day of the week and I would spend the entire day working on that one project with breaks as needed. This worked incredibly well for me for the last few years.

Unfortunately I now have an upcoming deadline for a very mentally draining project, so I need to find a new balance in my daily priorities and I'm struggling. I now need to work on that project daily for an hour or two at a time and also be able to keep up with the other tasks that need to be done both work wise and around the house. I can't tie anything to times, both because I only have one task that must be done at the same time every day, and because I'm an insomniac who's sleep schedule got massively out of control after a very stressful couple of months. Realistically, even though I'm now able to work on that, I'm not going to be able to get it completely under control before my deadlines hit. I'm doing my best to make sure I get at least the minimum amount of sleep every night I need to be functional the next day, but that could mean I'm up at 6 am or I'm struggling to wake up at 10 am. And I've caught myself multiple times telling myself that I can't do anything else until I get work done on that project, but then I get stuck and don't get anywhere and nothing else gets done because I'm too one track minded. Or if I try to work on other things first, I tend to fill my day getting everything else done and I'm wiped out and not up to working on that project.

I feel like working on things daily goes against my max productivity, but priorities have shifted and the business is expanding so I need to find a new way of doing things. Everything I've seen talks about tying new habits to existing ones, but as a general rule my days have almost zero consistency from one day to the next. That's why I did the schedule I did, because things like time blocking didn't have enough flexibility for what could happen daily. Does anyone have any suggestions for things that work when your daily life has almost no structure?