Blood Sugar levels?

As diabetes is, sadly, a progressive disease, it's quite possible for readings to alter over a year.   As for finger testing, I have often noticed different readings from tests done close together.   Which is why, other than the need for an immediate test, I tend to take more notice of the results of the regular blood testing my Diabetic nurse does.

Taking bloods from my fingers means I can wash my hands before doing so rather more easily than taking it from other parts of the body.

First - if you don't test very often - check the expiration date on the test strips.  You might be using expired test strips.  If you are - discard them and get new.

I am not sure if different parts of the body give different readings.  I do know that even testing from the same exact location can give two different readings even when taken at the same time.  Home meters have about a 10% error ratio.  They are not accurate enough to diagnose problems but they are accurate enough to be a guideline for a diabetic to help control their condition.  

Make sure what ever skin surface you are going to test from is clean and dry.  Something on the surface of your skin can impact your readings also.  

If you make sure your strips are not expired and you know your testing sight was "contaminated", then consult your doctor.  You MIGHT be showing the early signs of pre-diabetes - and YES - it can happen in less than a year.  

Yes, the capillaries in the surface skin, will give different readings in the same 1 or 2 minutes on the same meter.

The blood in the fingers is going to be close to what's taken from your veins (like what's taken during blood draws). Will also be different from your palms, forearms, thighs, feet. CGMs (continuous glucose monitoring). I did trials on two different CGMs, and when testing, they did IV blood draws every 15 mins, and compared those values to alternate test sites, forearm, thigh, fingers and palm. 

It COULD be that you have developed insulin resistance, which is a precursor to the development of type 2 diabetes, my friend.

What you should  do is speak with your own doctor who will know your medical history, and which medication(s) you've been prescribed.  (There are some medical conditions that make a person MORE LIKELY to develop insulin resistance, and your doctor will be aware of this.  There are also certain medications that can cause insulin resistance.  Again, your doctor will know this.)