Third baby dropping early

So this is my third baby and with my previous two I dropped at 35 weeks (first baby) and 36 weeks (second baby) and I had both baby at 38 weeks and 4 days. I am currently 31 weeks and baby has already dropped. I’m worried that I’m gonna go into preterm labor. Yesterday was my dr appointment and we had the conversation of what preterm labor would look like for me and baby. I’m just wondering if anyone else had experienced dropping this early.

Belly pictures for reference. Monday vs. this morning