Horse tack is for some reason a high fraud area.
However.
We use PP for all of our online selling including our own website and our public auction.
When you sent your Paypal payment to the seller, she got your email and postal address just as she would with an eBay sale.
Check that the PP payment went to the correct email address. And of course that it has been accepted.
If it has, the seller has no excuse for not shipping on cleared payment.
Tell her that politely. You can even play Ms. Nice Guy and give her your shipping address. Make sure it matches your PP address.
Ask her, politely, to send you the date of shipping and service used along with the tracking number* as soon as she has the parcel on its way. (on rereading you have done this. oops.)
If she doesn't have that done by Tuesday, the PP Resolution Centre is hidden under Tools on your account page.
The first suggestion is to contact the seller, which of course you have already done, so move on to the Claim.
If the seller cannot prove DELIVERY, not shipping, delivery, your payment will be refunded.
And of course, you have up to 180 days from payment to do this. But move now. Saddles are expensive!
*Which protects the seller of course, but puts her on notice that you did not just fall off the turnip truck.