Microeconomics is almost a branch of psychology, because it is fundamentally about behaviour

and:

Macroeconomics, on the other hand, is like thermodynamics. It deals with economic systems so large that the specific details of the economic behaviour of individuals are irrelevant

Are pertinent.  I think your observation that microeconomics is almost a psychology is exactly right.  However, I strongly disagree with your conclusion about macroeconomics, even though I believe your supporting statements about individual behavior being irrelevant, etc., to be correct.

I think with macroeconomics, what we're witnessing is group psychology and behavior.  In these fields, individual behavior and predictions are next to impossible while large groups tend to act predictably.  Thus, it is tempting to think of it as a science which can be mathematically explained.

But that's very wrong.  The seeming stability of macroeconomics is explained by group behavior and things like disbursal of responsibility which make larger groups more stable than smaller ones.

The key difference is that the laws of thermodynamics will still exist even if everyone in the world stops believing in them.  The same cannot be said of the economy.  You're correct that individual behavior has little effect, but group behavior does.

Maybe we can eventually make language a complete impediment to understanding. -Hobbes