idk how/if to tell SO about my depression

so i’ve been dating my SO for about 7 months, we aren’t official yet though. i have depression that kind of comes and goes in waves, by that i mean some days it’s a lot harder to deal with and i kinda succumb to it and stay in bed for days at a time etc.

it hasn’t been something i’ve wanted to tell him about for multiple reasons, maybe the biggest reason is because he and i aren’t super serious yet because we aren’t official, but i also don’t want it to change things and don’t want him to view me differently. i’m sure he’d be supportive and understanding and there for me, but i don’t want him to always look at me with sympathy or anything like that. and i don’t like the idea of telling him because i feel like him knowing puts a burden on him, something for him to worry about when i am having those bad days.

but it’s getting hard to keep it from him, and i also don’t like the feeling that i’m sort of lying to him. i had a bad day today and just stayed in bed for at least 12 hours, we were supposed to hangout but i told him something came up and i couldn’t today. he’s asking me nicely what i did today, but how am i supposed to tell him that all i did was stay in bed and take a 6 hour nap? :(

idk what to do.