I didn't mention a time limit/deadline in the message I sent her, which in hidsight, I should have mentioned it as a "just to give a fair warning/heads up" sort of thing. D:
But fortunately yesterday, she did end up paying for the items (or going by the note that was in the order/payment details, her son gave her the money in order to pay for the items and was writing the note in the order. The woman was in the hospital and had asked her son to log into her eBay to check if she had any messages. He read my previous message back to her and helped her out with the payment).
I am happy/relieved the items are paid for now and I did drop the package off at the post office in time afterwards yesterday (post officies are closed today in the US, right?), but a part of me still feels bad about the situation.
At least now I know what to do if a similiar situation like this happens in the future (on eBay, at least).
Thanks again so much for all the opinions/advice you guys gave me - it really helped me out with this, and you guys are all awesome!
I thought I had posted in here about it yesterday evening, but I guess I had accidently closed the tab before I sent the reply and didnt realize it. Dx
*goes to update the first post*