Yes the cerebellar tonsils (lowest part of the hind brain) are usually lower, on subsequent MRI slices to either side of the midsagittal view, as I can see yours are. In fact yours appear to almost abutt the Foramen Magnum (opening at the bottom of the skull) which can cause interruptions to the flow of CSF (Cerebro Spinal Fluid). This interruption to free-flow of CSF can result in raised intracranial pressure, often in these types of cases, which will not be discernible with a lumbar puncture (NOTE: see below, avoid lumbar punctures at all costs!)
What happens is that the low-lying cerebellar tonsils (sometimes referred to as Chiari 0) can act as a ‘bung’, so any raised intracranial pressure above it cannot normalise. Your description of symptoms of pain at the bottom of the skull (this can radiate down the neck and into the shoulder) and pain or pressure behind the eyes are typical of this sort of problem.
Having a lumbar puncture can worsen the affect of the ‘bung’ (and thus worsen symptoms) due to the lumbar puncture reducing the spinal CSF pressure and the raised intracranial pressure forcing brain matter into the hole at the bottom of the skull. Often in this type of case, the lumbar puncture shows a low or normal reading, when intracranially the pressure is raging!
I can also see from your scan that you have a Retroflex Odontoid and also a loss of ‘lordosis’ (the normal C shape of the spine) in your upper cervical region. The gap between the Opisthion (bottom back of the hole at the bottom of your skull) and the top of the back of C1 may be a little wide too, it’s difficult to tell but I notice this on a lot of people on this forum.
As for the bright white dot lower down your spine, I see it but I’m not sure what that is, did the radiologist not say ?