As OldUser said, sometimes you have to include individual accounts to prove you live at the same address (if you don't have a lot of co-mingled financial evidence. In some areas, it's impossible to have two names on utility accounts.
Best advice I can give is to put a statement in your cover letter that states how you have done your finances since you married - like you said in your original post. Explain that utilities were in your name before, and that you wanted to spare your spouse. This is your explanation...
Since I already had all my financial systems in place before my wife immigrated, I hadn’t moved most of our spending over. I was also trying to shield her from financial stress during the transition. That’s since changed - we’ve now been running shared expenses through our joint account consistently, but only for the past six months.
Put this in your cover letter to help explain what the officer is looking at.
Good luck!
Sukie in NY