Immediately go to the credit card you actually used to pay with. (Paypal is just the mediator.) There is probably a 1-800 number on the back of the card. Ask the customer rep about a chargeback.
Have your transaction dates and numbers as well as the amount of the payment on hand to help her process the refund.
In terms of eBay.
You have up to 60 days to leave feedback. The most effective feedback is calm and factual. "Paid Jan. 1/14. Not rec'd by March 12/14. Refund refused.'
At the same time you can leave Detailed Seller Ratings. The normal Rating is Five Stars. The lowest Rating is ONE STAR. No stars is a free pass.
Sellers whose DSRs drop below 4.3 have their ability to list and sell on eBay severely restricted.
In addition, you can leave a Response to any feedback, your own or the seller's indefinitely. Again the most effective Responses are calm and factual.
About shipping. Air Mail from China is quite fast, usually no more than the 15-20 days from the USA. Surface shipping is not worth the low cost as it can take two or three months.