Well, as I can't see the animated product, I can't say much...

One thing that I can suggest (if you haven't done it already) to make a more believable piece is to set up some opacity on the sprites.

Like a quick fade-in from 0 opacity to 100 over the course of its birth to maybe 3-5% of its life, and then slowly have it "die out" and lower the opacity over the rest of its life.

If you don't know how to mess around with ramps to do this, let me know and I'll elaborate