Welcome!! Yes, we all do that. I'm knitting socks right now in fingering weight yarn and dropped a stitch. Or two. I had to invest in a tiny crochet hook to pick it up easily. I keep various sizes in my knitting bag.
My mother used to crochet with those tiny hooks. Not me. I got one that's really small many years ago for pulling snags back through to the other side on sweaters and such.
I should never overestimate my basic arithmetic skills.