Placenta question!

Hello everyone! Please no judgment just a bit in my head, at my anatomy scan (19w) they told me I had posterior placenta.. I went to L&D for lack of movement at 25 weeks and they did an ultrasound to check for fluid levels and told me my placenta and anterior and posterior so it was like wrapped around. So fast forward to last week I was 33w and I had a 3D ultrasound and my son is head down and my placenta was on top of his head and it was all in his face… so my question is can your placenta move that much over a few weeks or does it just stay put?! I have an regular prenatalappointment tomorrow but does that not sound like previa placenta?! Or am I just thinking too much about it