I don't know if this is a normal trait for BPD but I've done the exact same thing too. There were a few older women who I've been too attached to & felt clingy towards. Before, I was always able to keep my clingy feelings to myself but I've lost that ability... Mother figures make me extremely happy & warm & fuzzy on the inside. I'm only a teenager but I never cared about making friends my own age, I wanted to be best friends with a second mom. The problem with these obsessions are that in no way am I trying to replace my real mom. We have a great relationship but I keep looking for motherly qualities in others for some reason.
I can definitely relate to how you feel. I feel humiliated when I suspect I've been rejected. I haven't been diagnosed with BPD but there's a good chance that I have it. I'm not sure if this problem is really associated with BPD but maybe having this disorder makes it easier to have obsessions like this...