I'm a female that's still in school, for the past few months, i've had a small, seemingly immovable and painless bump on my lowerback, near my spine.

Get it checked: It could be normal anatomy that you have not noticed previously. This is common among adolescents and teenagers as their body is developing from childhood to adulthood. However, not having the advantage of being able to see and feel this bump it is very difficult to judge. It could also be a mild congenital anomaly that has become noticeable. You could have a doctor evaluation this, to be sure.

Hard to say: There are a number of possibilities, even including a bone prominence from normal spinal anatomy. If it is not mobile it does suggest it is either bone or has a rigid attachment to bone. Consider being seen. A quick exam would probably be sufficient to tell the likely cause.