Is it "normal" for us with BPD to get some kind of satisfaction when people think of us / treat us as kids (in the sense of like vulnerable)? 

I personally generally love it when people think I'm younger than I am (and I'm 20, so this is not usual for my age), when someone says I'm "cute" or "adorable", or I am called things like "little one". 

My doctor says it is most likely due to neglect during childhood, so I'm still in a way looking to be "cared for". 

So is this common for BPD?