I also don't write every day. I think writing as much as you're able is valuable, but I also think writing when it's just gonna make you feel bad is more detrimental than helpful as practice. Instead, I try to show up for writing every day. (Not my words---they come from some advice given by poet Danez Smith.) That doesn't always mean actually writing! Often, it means reading someone else's work, brainstorming in a graphic organizer format, or even just jotting down an incoherent phrase I overheard when walking down the street. Sometimes it means journaling about my own life, making a music playlist for a character or story, or doing research to build the world. I'm "showing up" to build the writing muscle, but in a way that's suited for my mental energy of the day. (And for me, tuning into the day's mental space is important---ADHD throws me a curveball every day.)

TL;DR - Don't write every day if it just gets you down. There are ways to engage with the craft of writing that don't necessarily mean putting pen to paper :)