Hi Heidi,
At 33 weeks the cervix should be shaped like a 'tube' and closed. It should also be 2-3 cm long.
What the uss says is that your cx is thinning out at 1.6 cm long and funneling which means that it is more open at one end than the other.
Assuming no history of cx surgery, it suggests that you might go into labour early, although 33+ weeks is not that early. For instance, most hospitals dont give steroids (to mature babys lungs) or try to stop labour after 34 weeks, as babys generally do very well by this stage.
However, I think you need to see the m/w or the obstetric doctors (not GP) to discuss this situation, and reassure you. Its not that uncommon to have some funneling or even some dilatation if you have had babies before and most people do not have a scan at this stage and therefore don't know what their cx is doing, so don't be too concerned.
Your hospital might want to send you for another uss in 1-2 weeks to see if there is any further change, and many hospitals have a 'prematurity clinic' for this very scenario, although your pregnancy is probably a bit advanced for this clinic.
But I think you need to discuss this with your hospital, and please dont worry, at 33+ weeks your baby will be fine!
Hope this helps and good luck