YoY means that each value represents a comparison from two consecutive years. Just because some of the figures are a year apart does not make the chart, nor even those figures, YoY. You simply misnamed your post.

YoY means that you're comparing a moment or period from one year with the same moment or period the year before. It'd likely display data as a percentage drop from the year before. That's not what your graph is. Yours is just a graph of your weight.

Hey, I went to the shops today and bought 3 eggs and 2 loaves of bread. Eggs cost me $2 each and the bread was $5. In total I paid $16.

3 x 2 + 2 x 5 = 16

We do the multiplication first.

However, if we didn't, and we just worked from left to right, then this would happen:

3 x 2 + 2 x 5 = 40 (eggs then bread)

Or:

2 x 5 + 3 x 2 = 26 (bread then eggs)

It just doesn't matter what order I buy my eggs and bread if we do multiplication first.