It’s actually 7 cervical + 12 thoracic + 5 lumbar (you missed those). The 5 sacral vertebrae are fused into the sacrum in adulthood, so you might count that as one bone. The coccyx is also made of several rudimentary vertebrae, which are generally fused in adulthood.
So it’s at least 24 + 1 sacrum + 1 coccyx = 26, and possibly over 30 if you count the sacral and coccygeal vertebrae separately.