Welcome to the Ecuador forum, Lizzy.
----
Wow, it's been over a year since anybody before you has posted on this thread. No problem, it has now been revived.
----
You're doing a good job investigating from afar .. and making a wise decision to visit here before moving.
Based on the lifestyle you described I believe you are within budget, but not much to spare.
You can verify cost of living figures for Loja at www.numbeo.com ....
Your income well in excess of the $900 threshold for your case will qualify you as a pensioner-visa holder. Based on your post, your sister will absolutely qualify as your dependent.
After you obtain your residency visa and ID card, you and Sis can join the national IESS medical plan for under $100 a month for the both of you. The care you would receive has no deductibles for you to pay and you would qualify for care in hospitals in many cities around Ecuador. Please consider visiting the IESS hospital in or nearest to Loja when you visit.
You need to have a plan in case something happens to you in Ecuador and your sister would be, at least temporarily, on her own.
cccmedia