A nitrAte value of 0 is almost unheard of; how old are your tests? I have still in-date test kits that have been opened for over a year, and my ammonia is reading about 0.25, even for my tap water. I just ordered new kits to be on the safe side. You also need to get a KH kit, that may indicate why your pH is apparently so high. Test your source water too. As for doing water changes in the winter, I do them several times per year. I have a faucet it the basement that I can hook a hose to (so the hose doesn't freeze, I keep it in the basement, and I can add some warmer water, also). If you have this possibility, I would do a couple of 25% water changes a couple of days apart, to bring the ammonia level down.
I always buy the large size of SAFE, the powdered form of Prime, that Rich recommends, because you can add a tablespoons (or less, depending on need) every 48-72 hours, to control ammonia, nitrIte, nitrAte, chloramine, chlorine, and heavy metals. It's a great all-around water conditioner. Amazon can get it to you fast if you have a prime account.
I buy the 8 pound container, that's about $100, but it lasts a couple of years. Here's a smaller size, for your reference:
https://smile.amazon.com/Seachem-116...fe+seachem%27s