If a provider doesn’t respond to your initial email inquiry, is it worthwhile to follow up and email her again?  

Obviously the worst case scenario is she ignored the second email, but curious what others do.

Yes!

Your email might've somehow gotten into her spam folder and perhaps she missed it... or she was very very busy with other things going on in her personal life and hasn't had a chance to catch up on her emails

I would continue sending emails as long as you have interest.  

I would also move on to Plan B, or Plan C, as the one you are emailing may not respond at all.  

I've had connections fade only to start up again years later.  Things pick up pretty much where they left off.